POSTER

ABSTRACTS

Substitution-Driven Enhancement of the Néel Temperature in
the Noncollinear Magnet Mn3Sn: A Theoretical StudyYuta Toga1*, Katsuhiro Tanaka2, Satoru Nakatsuji2,3, and Takashi Koretsune4
1 JSR Corporation, Japan
2 Dept of Phys., Univ. of Tokyo, Japan
3 ISSP Univ. of Tokyo, Japan; JST-CREST, Japan; TSQS, Univ. of Tokyo, Japan; IQM, Johns

Hopkins Univ., USA
4 Dept. of Phys., Tohoku Univ., Japan
Abstract
The noncollinear magnet Mn3Sn is a key material for the realization of the antiferromagnetic
devices. The magnetic symmetry, which is strongly related to topological properties inmomentum space, has led to the observation of the anomalous Hall and Nernst effects [1] andeven the antiferromagnetic tunnel magnetoresistance (TMR) in an antiferromagnetic material[2]. The history of ferromagnetic studies implies that thermal fluctuations at the interface withinsulators degrade the TMR effect in the antiferromagnetic system. Therefore, from anapplication standpoint, we anticipate further increasing the Néel temperature of Mn3Sn, usually
420 K, is highly important.
This theoretical study aims to findsuitable elemental substitutions that may
enhance the Néel temperature in Mn3Sn. In
order to obtain the exchange couplings ofthe substitution systems, we use
Liechtenstein’s formula and the coherent
potential approximation (CPA), whichhave been implemented on the firstprinciples calculation using the KorringaKohn-Rostoker (KKR) Green’s-function
method, AkaiKKR [3]. Then, we built aclassical spin model and performed Monte
Carlo analysis to determine the Néel
temperature in the substituted systems (seeFigure).
In the presentation, we will discuss the Fig. Theoretical estimate of variation in the Néel
possibility of enhancing the Néel temperature temperature of Mn3Sn with elemental substitution.
of Mn3Sn by elemental substitutions and its
structural stability.
References[1] S. Nakatsuji, et al, Nature 527, 212 (2015); M. Ikhlas, et al., Nature Phys 13, 1085 (2017); S.
Nakatsuji and R. Arita, Annu. Rev. Condens. Matter Phys. 13 (2022).
[2] X. Chen, T. Higo, K. Tanaka, et al., Nature 613, 490 (2023).
[3] AkaiKKR (Machikaneyama, private version). http://kkr.issp.u-tokyo.ac.jp/

Anomalous Nernst effect in topological Fe3Ga1-xAlx polycrystals
Yangming Wang1, Susumu Minami1, Akito Sakai1 2, Hao Gu1, Taishi Chen1 2 3,
Zili Feng1 2, Daisuke Nishio-Hamane2, Satoru Nakatsuji1 2 4 5 6
1 Dep. Phys, UTokyo, 2 ISSP, UTokyo, 3 Dep. Phys, SEU
4 TSQSI, UTokyo, 5 CREST 6 Dep. Phys&Astron, JHU

The anomalous Nernst effect (ANE) is the thermoelectric generation of a transverse
voltage mutually perpendicular to both the magnetization and heat current in magnetic
materials. Recently, the material discovery and device design based on ANE attracted a lot of
attention due to its unique advantages of high efficiency and flexible structure [1]. A series of
stoichiometric topological materials [2-4] have been found to show large ANE in their single
crystal form. From the viewpoint of applications, it is also important to realize sizeable ANE
in the polycrystalline form at a low cost. However, the systematic investigation for ANE withdoping effect in polycrystalline materials is still lacking. Iron-based binary alloys Fe3X (X =Ga, Al) were discovered with record-large ANE at room temperature [2]. In this system, thehighly symmetric cubic structure ensures isotropic transport properties so the giant ANE isalso expected in high-quality polycrystalline samples.
We synthesized a series of Fe3Ga1-xAlx polycrystals by arc melting and measured theevolution of the magnetic and transport properties at room temperature. Interestingly, the sizeof ANE in Fe3Ga1-xAlx polycrystal is still comparable with Fe3Ga single crystal, which is also
consistent with the theoretical prediction. Considering that aluminum is more low-cost andabundant than gallium, this progress would be valuable for subsequent polycrystal-basedlarge-scale synthesis and device application.
[Reference][1] Mizuguchi M, Nakatsuji S. Science and technology of advanced materials, 2019, 20(1): 262-275.
[2] Sakai A, Minami S, Koretsune T, et al. Nature, 2020, 581(7806): 53-57.
[3] Guin S N, Vir P, Zhang Y, et al. Advanced Materials, 2019, 31(25): 1806622.
[4] Sakai A, Mizuta Y P, Nugroho A A, et al. Nature Physics, 2018, 14(11): 1119-1124.

Effect of Collective Spin Dynamics on Anomalous Transverse Transport:
Real-Time Calculation
Kohei Hattori1, Junta Iguchi1, Hikaru Watanabe2, Takuya Nomoto2 and Ryotaro Arita2, 3
1
2

Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan

Research Center for Advanced Science and Technology, The University of Tokyo, Meguro, Tokyo 153-8904, Japan
3

Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan

In recent years, the anomalous transverse conduction due to the topology in the real space has
attracted much attention [1]. The real-space topology of magnetic material shows up in noncoplanar
magnetic structures such as frustrated magnets and magnetic skyrmionic systems where the nontrivial
spin texture arises from the spin-orbit coupling and itinerant-electron-mediated interactions [2].
Recent experiment demonstrated that such a noncoplanar spin ordering with negligible magnetization
leads to sizable anomalous Hall effect which may be attributed to the emergent spin-charge coupling
related to the complex spin structure [3]. The identified spin texture comprised of multiple spins
allows for collective modes richer than conventional ferro- and antiferromagnets and is expected tointriguing interplay between spin and charge degrees of freedom in the induced responses as in caseof the recent study of photovoltaic effect [4].
To this end, we investigate the effect of the collective spin excitations on the anomalous Hall
response of noncoplanar magnet (Fig.1). We employ the real-time simulation method considering
time evolution of spin and electron coupled to each other. The obtained spectrum of optical Hall
response indicates that the collective spin excitations significantly influence the resonant and offresonant contributions (Fig. 2). We analyze the results in terms of symmetry and discuss which spinmodes affect the optical response of the electron system.

Fig. 1: All-in-all-out spin texture on triangular lattice.[5]Fig. 2: Optical Hall conductivity of noncoplanar magnets with(dashed line) and without including the collective-mode effect.

[1] N. Nagaosa, J. Phys. Soc. Jpn. 75, 042001 (2006).
[2] e.g., Y. Akagi et al., J. Phys. Soc. Jpn. 79, 083711 (2010)[3] H. Takagi et al., Nat. Phys.19, 961–968 (2023).
[4] J. Iguchi et al., arXiv:2311.12212.
[5] H. Watanebe et al., arXiv:2307.11560.

Unconventional non-Hermitian superfluid phase transition
induced by the interplay between exceptional manifolds and van
Hove singularity
Soma Takemori*, Kazuki Yamamoto, and Akihisa Koga
*Presenter
Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
Recently, ultracold atoms provided a practical platform for quantum simulation. Notably,much attention has been drawn to the dynamics of the non-Hermitian (NH) Hamiltonian
which is derived from extracting the conditional dynamics of open systems. In particular, NH
BCS theory has been proposed [1] and many studies have been conducted so far to explore
unconventional NH fermionic superfluid phase transition associated with exceptional
manifolds. While the increasing importance of investigating how exceptional manifolds
change conventional condensed matter physics, a unified understanding of their impact on NH
many-body phenomena has not been obtained yet.
In the poster session, we discuss the effects of exceptional manifolds on quantum manybody physics through studying the NH Hubbard model on a honeycomb lattice [2].
Remarkably, we show the emergence of an unconventional NH many-body phase diagram,where the dissipation-induced superfluid (DS) phase is anomalously enlarged when ELs passthrough van Hove singularity, giving rise to the cusp with the double-humped behavior.
Furthermore, we show the DS state appears with infinitesimal dissipation at the critical point.
This result reveals that exceptional manifolds can dominate the unconventional NH phasetransitions and exotic quantum phenomena in open quantum systems.

Figure 1. Phase diagram of the attractive Hubbard model with a complex-valued interaction.
References[1] K. Yamamoto et. al., Phys. Rev. Lett.123, 123601 (2019).
[2] S. Takemori, K. Yamamoto and A. Koga, arXiv:2309.16191.

Effect of alkali halide insertion on magnetic anisotropy at the
Fe/MgO interface
J. Chen1*, S. Sakamoto1, H. Kosaki1, and S. Miwa1, 2
1
2

The Institute for Solid State Physics, The University of Tokyo, Japan
Trans-scale Quantum Science Institute, The University of Tokyo, Japan

Perpendicular magnetic anisotropy (PMA) has attracted attention for magnetic tunnel
junctions owing to its high thermal stability and integration density. Recently, Nozaki et al.
reported that ultrathin LiF insertion enhances the interfacial PMA at the Fe/MgO interface while
maintaining the tunnel magnetoresistance [1, 2]. Motivated by these findings, we haveinvestigated the effect of inserting various alkali halide layers at the Fe/MgO interface andstudied the influence of electronegativity, spin-orbit interaction, and lattice matching on the
PMA energy [3, 4].
We fabricated epitaxial Fe/alkali halide (LiF, NaCl, CsI, or NaF)/MgO multilayers bymolecular beam epitaxy [Fig. 1(a)]. The surface crystallinity was examined by reflection highenergy electron diffraction, and the magnetic property was characterized by polar magnetooptical Kerr effect measurement. The effect of alkali halide insertion on interfacial PMA isshown in Fig. 1(b). We find that the LiF layer insertion up to 0.4 nm and the NaF layer insertion
up to 0.1 nm enhance the interfacial PMA energy, but thicker LiF and NaF insertion weaken it.
Both the CsI and NaCl insertion weaken the interfacial PMA energy monotonically with CsI or
NaCl thickness. Our results highlight the importance of Fe-F orbital hybridization for PMA
enhancement.

FIG 1. (a) Schematic sample structure. (b) Interfacial perpendicular magnetic anisotropy
energy (KI), for LiF, CsI, NaCl, and NaF sample
References[1] T. Nozaki et al., NPG Asia Mater 14, 5 (2022).
[2] S. Sakamoto et al., Phys. Rev. B 106, 174410 (2022).
[3] J. Chen et al., Phys. Rev. B 107, 094420 (2023).
[4] J. Chen et al., unpublished.

Hongchao Li
Abstract: Yang and Lee investigated phase transitions in terms of zeros ofpartition functions, namely, Yang-Lee zeros [C. N. Yang and T. D. Lee, Phys.
Rev. 87, 404 (1952); T. D. Lee and C. N. Yang, Phys. Rev. 87, 410 (1952)].
We show that the essential singularity in the superconducting gap is directly
related to the number of roots of the partition function of a BCS superconductor.
Those zeros are found to be distributed on a semicircle in the complex plane of
the interaction strength due to the Fermi-surface instability. A renormalizationgroup analysis shows that the semicircle theorem holds for a generic quantum
many-body system with a marginal coupling, in sharp contrast with the LeeYang circle theorem for the Ising spin system. This indicates that the geometryof Yang-Lee zeros is directly connected to the Fermi-surface instability.
Furthermore, we unveil the nonunitary criticality in BCS superconductivity thatemerges at each individual Yang-Lee zero due to exceptional points andpresents a universality class distinct from that of the conventional Yang-Leeedge singularity.

Magnetic damping of epitaxial Fe/Pt multilayer characterized bytime-resolved magneto-optical Kerr effect
E. Wei1*, S. Sakamoto1, J. Chen1, H. Kosaki1, T. Hatajiri1, and S. Miwa1, 2
1
2

The Institute for Solid State Physics, The University of Tokyo, Japan
Trans-scale Quantum Science Institute, The University of Tokyo, Japan

Magnetization damping enhancement is of great importance in both theoretical research
and applications such as magnetic storage. Mizukami et al. reported the damping as a functionof ferromagnet thickness with different nonmagnetic metals and showed that Pt has
significant damping compared to other metals [1]. Recently, Barati et al. calculated theGilbert damping of Co/nonmagnetic metal bilayers [2] while Azzawi et al. reported the Pt
thickness dependence using 10nm Co [3]. For opposite fabrication sequence, Swindells et al.
reported the difference between Pt/Co and Co/Pt bilayers [4]. In our research, we investigate
both ultrathin ferromagnet and nonmagnetic metals thickness and sequence dependence tostudy the intrinsic and extrinsic damping in Fe/Pt multilayer.
We use molecular beam epitaxial to fabricate V/Fe/Pt/MgO and V/Pt/Fe/MgO thin-films.
The crystallization is checked by reflection high-energy electron diffraction and the damping
is measured using time-resolved magneto-optical Kerr effect. We found that the relaxation
time of the free induction decay decreases as Pt thickness increases and reaches minimum ataround Pt 1nm. The relaxation time of V/Fe/Pt/MgO is shorter than V/Pt/Fe/MgO, whichmeans that the fabrication sequence will also affect the damping.

(a)

(b)

Fig.1 (a) Schematic of the sample. (b) Relaxation time dependence on Pt thickness of
V/Pt/Fe/MgO and V/Fe/Pt/MgO sample.
References[1] S. Mizukami et al., Jpn. J. Appl. Phys. 40, 580 (2001).
[2] E. Barati et al., Phys. Rev. B 90, 014420 (2014).
[3] S. Azzawi et al., Phys. Rev. B 93, 054402 (2016).
[4] C. Swindells et al., Phys. Rev. B 99, 064406 (2019).

Aspects of critical phenomena with boundary and defect:
Yoshitaka Okuyama1*, Tatsuma Nishioka2, and Soichiro Shimamori2*Presenter
1
Department of Physics, Faculty of Science, The University of Tokyo, Japan2
Department of Physics, Osaka University, Japan
Abstract (up to 200 words)
Critical phenomena are one of the long-standing subjects in theoretical physics. Whilethey are described by conformal field theory [1], when it comes to realistic setups, wemust include the effects of extended objects, which we call defects, such as impurities,
and the boundaries of the container of the experimental systems. We focus on a simple
but significant statistical model called the critical O(N) vector model and explore its
aspects in the presence of a defect. We take two different but complementary approaches,relying on the standard diagrammatic calculations combined with renormalization group
analysis and the axiomatic approach that postulates three mild assumptions encompassing
conformal symmetry of the system at criticality.
We demonstrate that both approaches agree well, and in particular, the analyticity ofcorrelation functions plays a critical role in resolving the spectrum of composite operators
within the axiomatic framework.
This presentation is based on [2,3], which deals with the critical O(N) model, but we here
present the case of the critical Ising model (N=1) as an illustration.

References[1] A. M. Polyakov, JETP Lett. 12 (1970)[2] T. Nishioka, Y. Okuyama, S. Shimamori, JHEP 03 (2023), 203[3] T. Nishioka, Y. Okuyama, S. Shimamori, JHEP 03 (2023), 051

Title: Uniqueness of the non-equilibrium steady state in open
quantum many-body systems
Hironobu Yoshida
Department of Physics, University of Tokyo, Japan
Abstract (up to 200 words)
We consider open quantum systems described by the Gorini–Kossakowski–Sudarshan–

Lindblad (GKSL) equation [1, 2]. In the presence of dissipation, quantum systems relax to a
non-equilibrium steady state (NESS), and the degeneracy of NESS is a fundamental propertyof open quantum systems. From a practical standpoint, it is important that the uniqueness of
the NESS is guaranteed in advance. For example, when calculating NESS using variational
methods, it is usually assumed that the NESS is unique.
In this poster, we present a simple proof of a sufficient condition for the uniqueness of thesteady states [3]. In contrast to previous studies, we focus on finite-dimensional systems,
which makes the proof much more concise. We also show that our criteria are also applicable
to open quantum systems with strong symmetry [4].
References[1] V. Gorini, A. Kossakowski, and E. C. G. Sudarshan, J. Math. Phys. 17, 821 (1976).
[2] G. Lindblad, Comm. Math. Phys. 48, 119 (1976)[3] H. Yoshida, arXiv: 2309.00335[4] B. Buča and T. Prosen, New J. Phys. 14, 073007 (2012).

Title:Time-dependent Gutzwiller simulation of Floquet topologicalsuperconductivity
T. Anan1*, T. Morimoto1, and S. Kitamura1*Presenter
1
Department of Applied Physics, The University of Tokyo, Japan
Abstract (up to 200 words)
Periodically driven systems provide a novel route to control the topology of quantum
materials. In particular, Floquet theory allows an effective band description of periodicallydriven systems through the Floquet Hamiltonian. Along this direction, it was theoretically
predicted that d-wave cuprate superconductors irradiated with circularly-polarized light (CPL)
exhibit Floquet topological superconductivity purely from the many-body effect by
employing the high frequency expansion (HFE) and deriving Floquet t–J model [1]. Here, we
study the time evolution of d-wave superconductors irradiated with CPL [2]. We observe thedevelopment of the idxy-wave pairing amplitude along with the original dx2−y2-wave order
upon gradual increasing of the field amplitude, owing to the three-site term with broken timereversal symmetry (as shown in Figure). We further numerically construct the Floquet
Hamiltonian for the steady state, with which we identify the system as the fully-gapped d+idwave superconducting phase with a nonzero Chern number. We explore the low-frequency
regime where the HFE breaks down, and find that the topological gap of an experimentallyaccessible size can be achieved at much lower laser intensities.
References[1] S. Kitamura and H. Aoki, Commun. Phys. (2022)[2] T. Anan, T. Morimoto, and S. Kitamura arXiv: 2309.06069

Title: Formation and evolution of galaxies in the early Universe by
3D hydrodynamics simulation
Y. Nakazato1*, D. Ceverino2, and N. Yoshida1, 4, 5
*Presenter
1
Department of Physics, The University of Tokyo, Japan
2
Universidad Autonoma de Madrid, Spain
3
CIAFF, Facultad de Ciencias, Universidad Autonoma de Madrid, Spain
4
Kavli Institute for the Physics and Mathematics of the Universe (WPI), UT Institute forAdvanced Study, The University of Tokyo, Japan
5
Research Center for the Early Universe, School of Science, The University of Tokyo, Japan
Abstract (up to 200 words)
The observation of the most distant galaxies had been one of the most cutting-edge research
topics in astrophysics. In particular, James Webb Space Telescope (JWST), operational since2022, has unveiled galaxies existing just 0.5 billion years after the BigBang, evidenced by thethe detection of oxygen emission lines. In this study, we perform three-dimensionalhydrodynamical simulation and follow formation and evolution of early galaxies within the firstbillion years after the BigBang. In order to compare simulated galaxies and observed ones, wedevelop a physical model of radiation field and calculate spatially resolved oxygen line
emission from each galaxy. We show that the early universe is dense and galaxy merger
happens frequently, which leads the surrounding gas to be tidally compressed and form clumpy
structure. Through the merger-induced gas compression, galaxies experience bursty starformation. The formed stars finally end in supernovae explosion and expel a significant
abundance of metal (oxygen) to galaxies. Some massive galaxy samples are already metalenriched at the cosmic age of 0.8 billion year, whose metal abundance is comparable to thepresent-day galaxies[1]. Our theoretical predictions of clumpy morphologies driven by galaxygalaxy merger and subsequent chemical evolution are consistent with the latest JWST
observations.
References[1] Y. Nakazato, N. Yoshida, D. Ceverino, 2023, The Astrophysical Journal, 953, 140,
https://doi.org/10.3847/1538-4357/ace25a
The Figure is attached below

The relationship between stellar mass and metallicity of galaxies at a cosmic age of
5-10 billion years (redshift z=6-9). The distribution of galaxy samples from thesimulation is shown as a band. Plots are the results of JWST observation. The topleft panels show a simulated galaxies and observed galaxies with clump structures.
Merger movie can be obtained from here.

Bulk photovoltaic effect in antiferromagnet: Role of collective spin
dynamics
Junta Iguchi1＊, Hikaru Watanabe2, Yuta Murakami3, Takuya Nomoto2 andRyotaro Arita2, 3＊

Presenter
Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
2
Research Center for Advanced Science and Technology, The University of Tokyo, Meguro,
Tokyo 153-8904, Japan
3
Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
1

Inspired by recent advancements in the bulk photovoltaic effect which can extend
beyond the independent particle approximation (IPA), we investigate the influence ofcollective spin dynamics on photocurrent generation in an antiferromagnetic system [1]. The
photovoltaic effect in magnets has gained much attention due to its distinct features, such as
the large photocurrent response inherent to the injection current mechanism and its tunability
by manipulating the spin textures [2]. In such spin systems, the effect of spin dynamics is yet
to be explored.
We employ a unified framework for real-time simulations of conduction electrons andlocalized spin moments. In the linear and photocurrent conductivity spectra, we observe peaks
below the bandgap regime, attributed to the resonant contributions of collective modes,
alongside broadband modifications resulting from off-resonant spin dynamics. Notably, we
reveal that the emergence of spin dynamics allows various types of photocurrents, which areabsent in the IPA framework. In terms of the tunability of the photocurrent, we show that we
can tune the feedback strength from spin dynamics by modulating the amplitude of theexternal field. Here, we emphasize the importance of energy scale proximity between
electronic and spin degrees of freedom in enabling efficient feedback between them.

References[1] arXiv:2311.12212[2] T. Kaneko et al, Phys. Rev. Lett. 127, 127402 (2021)[3] S. Okumura et al. Phys. Rev. B. 104, L180407 (2021)

Title: Possible rattling and anharmonicity enhanced
superconductivity in Sc6MTe2 (M= Fe, Co, Ni)
A. Ming-Chun Jiang1,2*, B. Ryota Masuki3 , C. Atsushi Togo4,5, D.
Guang-Yu Guo2,6, E. Ryotaro Arita1,7

1

RIKEN, Center for Emergent Matter Science, Japan2
Department of Physics and Center for Theoretical Physics, National Taiwan
University, Taiwan
3
Department of Applied Physics, University of Tokyo, Japan
4
Research and Services Division of Materials Data and Integrated System, National
Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
5
Center for Elements Strategy Initiative for Structural Materials, Kyoto University,
Sakyo, Kyoto 606-8501, Japan
6
Physics Division, National Center for Theoretical Sciences, Taipei, Taiwan
7
Research Center for Advanced Science and Technology, University of Tokyo, Japan
Motivated by the recent discovery of superconductivity in Sc6MTe2 (M= 3d, 4d, 5delements) [1], we investigate the role of electron-phonon coupling in Sc6MTe2 (M=Fe,
Co, Ni) based on density functional perturbation theory and self-consistent phonon
theory. Our predicted transition temperatures, importantly, reproduce the chemical
trend. We attribute superconductivity to the electronegativity difference between Sc
and M, which suppresses the magnetism of Fe, Co, and Ni, possibly influencing thespin fluctuations in Sc, avoiding the suppression of the superconductivity. In the M =Fe and Co cases, we observe rattling phonon modes contributing to strong electronphonon coupling. For M = Fe, imaginary phonon modes indicative of anharmonicity
are detected. The renormalized soft phonon bands lead to a prominent plateau in the
Eliashberg spectral function, enhancing superconductivity. Our research suggests a
strategy for designing phonon-mediated superconductors using d-elements,
integrating non-superconducting and magnetic components. This study further
emphasizes the critical roles of rattling modes and anharmonicity in modulating
electron-phonon interactions and, consequently, superconductivity.
References[1] Y. Shinoda et al., J. Phys. Soc. Jpn. 92, 103701 (2023).

Theory of the Inverse Edelstein Effect using Boltzmann Equation
M. Yama1*, M. Matsuo2,3,4, and T. Kato1*Presenter
1
Institute for Solid State Physics, The University of Tokyo, Japan
2
Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, China
3
RIKEN Center for Emergent Matter Science (CEMS), Japan
4
Advanced Science Research Center, Japan Atomic Energy Agency, Japan
Abstract
In two-dimensional electron systems with Rashba spin-orbit coupling, a spin-to-charge
conversion phenomenon called the inverse Edelstein effect occurs. This effect has been
experimentally studied in various materials such as Ag/Bi [1], surface states of topologicalinsulators [2], and semiconductors [3]. These studies examine the conversion from spincurrents induced by spin pumping to currents. To date, there have been few theoretical studies
based on microscopic descriptions of this phenomenon using spin pumping.
In our study [4], we construct a theory of the inverse Edelstein effect with spin pumping in ajunction system (Fig. 1) of a ferromagnetic insulator (FI) and a two-dimensional electron gas(2DEG) with Rashba and Dresselhaus spin-orbit couplings using the Boltzmann equation [5].
In this study [4], the theory is constructed using a microscopic Hamiltonians. We clarify thedependence of the current produced by this effect on the magnetization orientation in the
ferromagnetic insulator, on the frequency of the microwave irradiated from outside, and on
the ratio of the sizes of the Rashba and Dresselhaus spin-orbit couplings. In this presentation,
we will report on these results.
References[1] J.-C. R. Rojas-Sanchez, et al., Nat. Commun. 4, 2944 (2013)[2] Y. Shiomi, et al., Phys. Rev. Lett. 113, 196601 (2014)[3] L. Chen, et al., Nat. Commun. 7, 13802 (2016)[4] M. Yama, M. Matsuo, and T. Kato, Phys. Rev. B 108, 144430 (2023)[5] Y. Suzuki and Y. Kato, Phys. Rev. B 107, 115305 (2023)

Fig. 1 Setup of our study

Title: Anomalous crystal shapes induced by topological phases
protected by crystal symmetries
Yutaro Tanaka1*, Tiantian Zhang2, Makio Uwaha3, and Shuichi Murakami1*Presenter
1
Department of Physics, Tokyo Institute of Technology, Japan
2
CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese
Academy of Sciences, China
3
Science Division, Center for General Education, Aichi Institute of Technology, Japan
Abstract
It is now well-studied how chemical bondings determine crystal shapes via dependence of
surface energies on surface orientations. One can expect that topological surface states of
topological materials may affect surface energies and crystal facets in an unconventional way.
Here we show that the surface energy of glide-symmetric topological crystalline insulators(TCI) depends on the surface orientation in a singular way via the parity of the Miller index(Fig. 1) [1]. This singular surface energy of the TCI affects equilibrium crystal shapes, resulting
in the emergence of unique crystal facets of the TCI [1]. In addition, we show that when a
topological insulator transforms into a second-order topological insulator by adding a magnetic
field, the crystal shape changes in a peculiar way [2].

Fig. 1. Equilibrium crystal shapes of (a) trivial insulator and (b) TCI.
References[1] Y. Tanaka, T. Zhang, M. Uwaha, and S. Murakami, Phys. Rev. Lett. 129, 046802 (2022).
[2] Y. Tanaka and S. Murakami, Phys. Rev. B 107, 245148 (2023).

Colossal negative magnetoresistance in field-induced Weyl
semimetal of magnetic half-Heusler compound
Kentaro Ueda*1, Tonghua Yu1, Motoaki Hirayama1,2, Ryo Kurokawa1,
Taro Nakajima2,3, Hiraku Saito3, Markus Kriener2, Manabu Hoshino2, Daisuke
Hashizume2, Taka-hisa Arima2,4, Ryotaro Arita2,5, and Yoshinori Tokura1,2,6
1* Presenter, e-mail: ueda@ap.t.u-tokyo.ac.jp
Department of Applied Physics and Quantum Phase Electronics Center (QPEC), Universityof Tokyo, Japan
2
RIKEN Center for Emergent Matter Science (CEMS), Japan
3
Institute for Solid State Physics, University of Tokyo, Japan
4
Department of Advanced Material Science, University of Tokyo, Japan
5
Research Center for Advanced Science and Technology, University of Tokyo, Japan
6
Tokyo College, University of Tokyo, JapanThe discovery of topological insulators and semimetals triggered enormous interest in
exploring emergent electromagnetic responses in solids. Particular attention has been focusedon ternary half-Heusler compounds, whose electronic structure bears analogy to the
topological zinc-blende compounds while also including magnetic rare-earth ions coupled to
conduction electrons [1]. However, most of the research in this system has been in bandinverted zero-gap semiconductors such as GdPtBi [2], which still does not fully exhaust thelarge potential of this material class. Here, we report a less-studied member of half-Heusler
compounds, HoAuSn, which we show is a trivial semimetal or narrow-gap semiconductor atzero magnetic field but undergoes a field-induced transition to a Weyl semimetal, with anegative magnetoresistance exceeding four orders of magnitude at low temperatures. The
combined study of Shubnikov-de Haas oscillations and first-principles calculation suggeststhat the exchange field from Ho 4f moments reconstructs the band structure to induce Weyl
points which play a key role in the strong suppression of large-angle carrier scattering. Ourfindings demonstrate the unique mechanism of colossal negative magnetoresistance andprovide pathways towards realizing topological electronic states in a large class of magnetic
half-Heusler compounds.
[1] Chadov, S. et al., Nat. Mater. 9, 541-545 (2010); Lin, H. et al., Nat. Mater. 9, 546-549(2010).
[2] Suzuki, T. et al., Nat. Phys. 12, 1119 (2016); Hirschberger, M. et al., Nat. Mater. 15, 1161
(2016).
Reference:
Kentaro Ueda et al., Nature Communications 14, 6339 (2023)
DOI: 10.1038/s41467-02341982-4

Electronic phase control of potassium-intercalated layered MoS2 devices
Alec Romagosa1, Ricky D. Septianto1, Hideki Matsuoka1, Yoshihiro Iwasa1,2
1RIKEN Center for Emergent Matter Science, Wako, Saitama, Japan 2 Department of Applied

Physics, The University of Tokyo, Japan
Though MoS2 has been examined heavily for its properties as a relatively easily used and exfoliatedtransition metal dichalcogenide with promising electronic properties as a semiconductor, it has more
recently been studied as a 2D superconductor, for instance in heterostructures involving proximity
induced superconductivity. [1] One of the most promising means for inducing 2D superconductivity is
the construction of an electronic double-layer transistor (EDLT). [2] In this approach, an electron
accumulation region is formed in the topmost layer, and a dome-like superconducting region can beseen when compiling temperature to carrier density phase diagram [3]. Intercalation of alkali metals
or hydrogen into the van der Waals gap of the layered 2D materials has also been attracting increased
interest as a means of quantum phase control. For instance, it has been shown to cause room
temperature ferromagnetism in Li intercalated Fe3GeTe2 [4] and BCS-BEC crossover in ZrNCl [5].
As for the intercalation of alkali metals into MoS2, although existence of the superconducting
phase is known for many years, the electronic phase diagram has not been explored. Powder
diffraction experiments have shown evidence of structural phase change from 2H to 1T and 1T’ phases,from intercalation of a polycrystalline sample, with different superconducting critical temperatures at
each phase. [6] In this study, we have performed an ionic gating experiment to understand thesuperconducting phase diagram of potassium intercalated MoS2.
By precisely controlling the gating processes,
we discovered multiple emergent electronic phases.
One is the low carrier density state that exhibits a
metal-insulator transition at approximately 80 K, whichappears to be a charge density wave (CDW) state.
When the carrier density is increased, we found two
metallic states: one showing superconductivity at Tc =5.5 K, and the other a highly metallic state with noapparent
superconducting transition down to 2K. Based on this,
we are constructing a carrier density phase diagram
based on Hall-effect mobility measurements. At highlevels of intercalation-induced carrier density, an
irreversible transition to an unknown phase has beenfound using Raman spectroscopy.

Fig. 1 Crystal structureof K intercalated
MoS2.

[1] J. Daniel et al., ACS Nano 2020, 14, 3, 2718–2728 [2] J. M. Lu et al. , Science 350, 1353-1357 (2015).
[3] J. T. Ye et al., Science 338, 1193 (2012).
[4] Y. Deng et al. Nature 563, 94 (2018).
[5] Y. Nakagawa et al., Science 372, 190 (2021).
[6] R. Zhang et al., Nano Lett. 2016, 16, 1, 629–636

Title: Decay spectroscopy and delayed-neutron measurements ofneutron-rich nuclei from Os to Po at RIBF
T.T. Yeung1,2*, S. Nishimura2, V.H. Phong2, H. Sakurai2,1 M. Niikura2, K.
Kokubun1, and R. Mizuno1, for the BRIKEN collaboration*Presenter
1
The University of Tokyo, Japan
2
RIKEN Nishina Center, Japan
Abstract (up to 200 words)
The neutron-rich N ~ 126 region is important to r-process calculation around the thirdabundance peak and study of shell evolution across N = 126 shell closure. However, only
limited information about their nuclear properties is available. Experimental measurements ofnuclear properties of more exotic nuclei are essential to verify various theoretical models [1,2].
We will present recent progress in the BRIKEN experiment [3] at RIBF, RIKEN Nishina
Center. Particle identification of more than 40 isotopes from Os to Po was confirmed by the
BigRIPS separator and the silicon dE telescope. For the first time at RIBF, half-lives and betadelayed neutron-emission probabilities (Pn) of N ~ 126 exotic isotopes were measured by the
WAS3ABi β-counting system [4] and the 3He proportional counters [5]. We expect half-livesof 46 isotopes, including 21 measured for the first time. New isomers were observed byconversion electron-γ coincidences using WAS3ABi and high-purity germanium (HPGe)clover detectors. The analysis methods used and selected preliminary results will be discussed.
References[1] P. Möller et al., At. Data Nucl. Data Tables, 125, 1-192 (2019).
[2] T. Suzuki et al., Astrophys. J. 859(2), 133 (2018).
[3] J. Wu et al., RIBF NP-PAC Proposal, NP1712-RIBF158 (2017).
[4] S. Nishimura, Prog. Theor. Exp. Phys., 2012(1), 03C006 (2012).
[5] A. Tolosa-Delgado et al., Nucl. Instrum. Methods. Phys. Res. A, 925-133 (2019).

Spin dynamics in easy-plane triangular antiferromagnet
CsFeCl3 under pressures near the quantum critical point
Zijun Wei1*, Shinichiro Asai1, Hodaka Kikuchi1, Shinichi Itoh2, Masuda Takatsugu1
1
Institute for Solid State Physics, the University of Tokyo
2
Institute of Materials Structure Science, KEK
Abstract
We performed inelastic neutron scattering experiment under pressures in an easy-plane
triangular antiferromagnet CsFeCl3. Our investigation focused on examining themagnetic properties near the quantum critical point (QCP). Notably, we observed theobservation of a magnetic Bragg Peak near the QCP, substantiating magnetic longrange order at low temperatures. While the well-defined magnetic excitation spectrum
was approximately reproduced by the Extended Spin-Wave Theory (ESWT) [1], thepresence of broadened excitations unveils the existence of exotic spin dynamics within
CsFeCl3.
References[1] S. Hayashida et al., Sci. adv. 5, eaaw5639 (2019).

Valley-Selective Phonon-Magnon Scattering in Magnetoelastic
Superlattices
Liyang Liao1*, Jorge Puebla2, Junyeon Kim2, and Yoshichika Otani1,2*Presenter
1
Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
2
Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
Abstract
Phonons and magnons are engineered by periodic potential landscapes in phononic [1] andmagnonic crystals [2], and their combined studies may enable valley phonon transport tunable
by the magnetic field [3]. Through nonreciprocal surface acoustic wave transmission, we
demonstrate valley-selective phonon-magnon scattering in magnetoelastic superlattices. The
lattice symmetry and the out-of-plane magnetization component control the sign ofnonreciprocity. The phonons in the valleys play a crucial role in generating nonreciprocaltransmission by inducing circularly polarized strains that couple with the magnons. The
transmission spectra show a nonreciprocity peak near a transmission gap, matching thephononic band structure. Our approach provides a way to apply valley phonon in the bulk
transport regime. It demonstrates the periodically modulated magnon-phonon coupling as a
new tool for controlling the valley phonon transport [4].

References[1] S. Y. Yu et al., Nat. Mater. 15, 1243 (2016).
[2] A. V. Chumaket al., Phys. Rev. Lett. 108, 257207 (2012).
[3] E. Thingstad et al., Phys. Rev. Lett. 122, 107201 (2019).
[4] L. Liao et al., Phys. Rev. Lett. 131, 176701 (2023).

Construction of symmetry-adapted Closest Wannier models
using multipole basis
Rikuto Oiwa1*, Akane Inda2, Satoru Hayami2, Takuya Nomoto3, Ryotaro Arita1,3,and Hiroaki Kusunose4
1 RIKEN, Wako, Saitama 351-0198, Japan
2 Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
3 Research Center for Advanced Science and Technology, University of Tokyo, Komaba, Tokyo 153-8904, Japan
4 Department of Physics, Meiji University, Kawasaki 214-8571, Japan

Recently, T. Ozaki has developed a non-iterative method for constructing the closest
Wannier functions for a given set of atomic orbitals [1]. In this presentation, we will show themethod for the symmetrization of the closest Wannier models and its applications.
In the closest Wannier formalism, by introducing the smoothly varying window function forthe projection of the atomic orbitals onto the Kohn-Sham orbitals, disentanglement of bands isachieved without any iterative calculations. However, no symmetry constraint is applied inthis procedure, leading to unexpected symmetry breaking. We have recently developed amethod for the symmetrization of the closest Wannier models, which is achieved byexpressing the Hamiltonian as the linear combination of the symmetry-adapted multipole
bases (SAMBs) [2] belonging to the fully symmetric irreducible representation. In thisformalism, the linear coefficients of the SAMBs are automatically determined by thesymmetrization procedure.
In the presentation, we demonstrate the advantages of our method. For example, by using
the method, we have constructed a symmetry-adapted Closest Wannier model of the chiralTellurium crystal. Expressing the model in terms of the SAMBs, we have found the dominantcomponents in both the local and itinerant terms corresponding to the electric toroidal
quadrupole, Gu.
References[1] T. Ozaki, arXiv:2306.15296, (2023).
[2] H. Kusunose, RO, and S. Hayami, Phys. Rev. B 107, 195118 (2023).

Title: On-chip strong coupling between spin waves and surface
acoustic waves
Y. Hwang1, 2*, J. Puebla2, K. Kondou1, C. Gonzalez-Ballestero3, 4, H. Isshiki1, C.
Sánchez Muñoz5, L. Liao1, F. Chen6, W. Luo6, S. Maekawa2, 7, 8, and Y. Otani1, 2*Presenter
1
Institute for Solid State Physics, University of Tokyo, Japan
2
CEMS, RIKEN, Japan
3
Institute for Quantum Optics and Quantum Information of the Austrian Academy of
Sciences, Austria
4Institute for Theoretical Physics, University of Innsbruck, Austria
5Departmento de Física Teórica de la Materia Condensada and Condensed Matter Physics
Center (IFIMAC), Universidad Autónoma de Madrid, Spain
6
School of Integrated Circuits, Wuhan National Laboratory for Optoelectronics, Huazhong
University of Science and Technology, China
7
Advanced Science Research Center, Japan Atomic Energy Agency, Japan
8
Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, China
Hybridized states are distinctive of the strong coupling regime, wherein the coupling strength
exceeds the relaxation rates of each coupled state. Under this condition, the coupled systemdemonstrates coherent energy transfer [1]. Numerous studies reported the achievement ofstrong magnon–phonon coupling [2–5]. However, a notable challenge arises from thepronounced dependence of the phonon wavelength on the dimensionality of the active
magnetic layer within the structure [6]. This dependence restricts the independent control ofthe phonon wavelength and the size of the magnet, impeding the potential to amplify the
coupling strength by increasing the volume of the magnet. To address this challenge, we
implemented an on-chip surface acoustic wave (SAW) resonator [7] featuring a thin
ferromagnetic film. This configuration allows for systematically tuning the size of the magnet
while keeping the phonon wavelength consistent and enhances the shear strain of SAWs [8]which strongly couples to magnons [5]. Here we
present the experimental observation of strong
coupling between magnons and SAW phonons byanalyzing dispersion anticrossings. As expected,
we detect a monotonic increase in the couplingstrength by expanding the ferromagnetic film
thickness. Our work substantially advances
fundamental research and develops devices basedon magnon–phonon hybrid quasiparticles.
References[1] Z. Kurucz, et al., Phys. Rev. A 83, 053852 (2011).
[2] T. Kikkawa, et al., Phys. Rev. Lett. 117, 207203 (2016).
[3] C. Berk, et al., Nat. Commun. 10, 2652 (2019).
[4] K. An, et al., Phys. Rev. B 101, 060407(R) (2020).
[5] T. Hioki, et al., Commun. Phys. 5, 115 (2022).
[6] S. Mondal, et al., ACS Appl. Mater. Interfaces 10, 43970 (2018).
[8] B. Zhang, et al., Jpn. J. Appl. Phys. 56, 07JD02 (2017).

Title: Classification of Lifshitz invariant in multiband superconductors and its
application to Leggett modes
R. Nagashima1*, S. Tian2, R. Haenel2,3, N. Tsuji1,4, and D. Manske2*Presenter
1
The University of Tokyo, Japan
2
Max Planck Institute for Solid State Research, Germany
3
University of British Columbia, Canada
4
RIKEN, Japan
Abstract (up to 200 words)
Leggett mode is one of the collective modes originating from the phase difference between the orderparameters of a multiband superconductor. Previously, it has been pointed out that the Leggett modecan be optically excited in the linear response regime, as demonstrated in a one-dimensional model for
multiband superconductors [1].
However, it has not been known which crystallographic point group, particularly in two-dimensional
materials, shows the Leggett mode in the linear response regime. Here we identify the linear coupling
term in the Ginzburg-Landau free energy as the so-called Lifshitz invariant, which has one spatial
derivative and is antisymmetric under the order parameter exchange. We classify all pairs of irreducible
representations of order parameters in the crystallographic point groups that allow for the existence of
the Lifshitz invariant. Using the classification, we can judge whether or not each material can show theLeggett mode in the linear response regime. We also show that the Kagome superconducting materials[2] are good candidates for observing the Leggett mode. To demonstrate this, we constructed a Kagome
superconducting model with the Lifshitz invariant and calculated the linear optical conductivity [3].

A schematic picture of the free energy of a three-band-superconductor.

References[1] T. Kamatani, et al., Phys. Rev. B 105, 094520 (2022)[2] K. Jiang, et al., Natl. Sci. Rev. nwac199 (2022)[3] R. Nagashima, et al., Phys. Rev. Res. To be published.

Observation of domain wall in chiral antiferromagnet
Moeta Tsukamoto*1, Zhewen Xu2, Tomoya Higo1,3,4, Kouta Kondo4,5, Kento
Sasaki1, Mihiro Asakura1, Shoya Sakamoto3, Pietro Gambardella2, Shinji
Miwa3,4,6, YoshiChika Otani3,4,5,6, Satoru Nakatsuji1,3,4,6,7, Christian Degen2,
Kensuke Kobayashi1,6,8*Presenter
1
Dept. of Phys. Univ. Tokyo, Japan2
ETH Zurich, Switzerland
3
ISSP Univ. Tokyo, Japan
4
JST CREST, Japan
5
RIKEN CEMS, Japan
6
TSQS Inst. Univ. Tokyo, Japan
7
Johns Hopkins Univ., Japan
8
IPI Univ. Tokyo, Japan

Abstract (up to 200 words)
Magnetic domain wall in chiral antiferromagnet is an important factor in developing fastmagnetic memory. The fast speed of the domain wall driven by the current guarantees theperpendicular magnetic memory to move fast, but the domain wall structure, the physics
background, has yet to be revealed. Here, we observed the domain wall between
perpendicular magnetization of cluster magnetic octupole in Mn3Sn[1,2]. Magnetic domains
with over hundreds nm scale are observed using nanoscale scanning diamondmagnetometry[3]. Reconstructed magnetization is the most consistent with perpendicularpolarization in all axes, including the tilted. The domain wall dominated by exchangeinteraction, not grain boundary, tells us the physical properties and the domain wall chirality.
Detailed observation of the domain wall powerfully assists in developing materials anddevices. Simultaneous revealing of the physical background contributes to understanding thenon-trivial domain and spin structure.
References[1] S. Nakatsuji, et al., Nature 527, 212(2015).
[2] T. Higo, K. Kondou et al., Nature, 607, 474(2022).
[3] S. V ́elez, et al., Nat. Coomun. 10, 1 (2019).

Multi-step topological transitions among
meron and skyrmion crystals in a centrosymmetric magnet
H. Yoshimochi1*, R. Takagi2, 3, J. Ju2, N. D. Khanh1, H. Saito2,
H. Sagayama4, H. Nakao4, S. Itoh4, 5, Y. Tokura1, 6, 7,
T. Arima6, 8, S. Hayami9, T. Nakajima2, 5, S. Seki1, 10
1Department of Applied Physics, University of Tokyo, Tokyo 113-8656, JapanThe Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-0882, Japan
3
PRESTO, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
4
Institute of Materials Structure Science,High Energy Accelerator Research Organization, Tsukuba 319-1195, Japan
5
Materials and Life Science Division, J-PARC Center, Tokai 319-1195, Japan
6
RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
7
Tokyo College, The University of Tokyo, Tokyo 113-8656, Japan.
8Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
9
Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan10
Institute of Engineering Innovation, University of Tokyo, Tokyo 113-0032, Japan
2

Topological swirling spin textures, such as skyrmions and merons, have recently attracted
much attention as a unique building block for high-density magnetic information devices. The
controlled transformation among different types of such quasi-particles is an important
challenge, while it was previously achieved only in a few non-centrosymmetric systems
characterized by Dzyaloshinskii-Moriya interaction[1].
Here, we report an experimental discovery of multi-step topological transitions among avariety of meron and skyrmion crystal states in a centrosymmetric magnet GdRu2Ge2[2]. By
performing the detailed magnetic structure analysis based on resonant X-ray and neutron
scattering experiments as well as electron transport measurements, we have found that thiscompound hosts periodic lattice of elliptic skyrmions, meron/anti-meron pairs, and circularskyrmions as a function of external magnetic field (Figure 1). Such an intricate manner of
topological magnetic transitions is well reproduced by a theoretical model considering thecompetition between Ruderman-Kittel-Kasuya-Yosida interactions at inequivalent wave
vectors. The present findings demonstrate that even a simple centrosymmetric magnet withcompeting interactions can be a promising material platform to realize a richer variety ofnanometric magnetic quasi-particles with distinctive symmetry and topology, whose stability
may be tunable by various external stimuli.
Phase I

Phase II (SkX I)

Phase III

Phase IV (SkX II)

Phase VNsk = 0Nsk = -1

Nsk = 0Nsk = -1

Nsk = 0Bmz (a.u.)
-1.0

1.0

1.0
0.8
0.6
0.4
0.2
0

Figure 1: Overall magnetic structures in GdRu2Ge2.
Two kinds of SkXs are realized in phases II and IV.

[1] X. Z. Yu et al., Nature 564, 95 (2018). [2] H. Yoshimochi et al., Nature Physics (in press).

Resonant surface acoustic wave absorption in YIG
You Ba1*, Jorge Puebla1, Kei Yamamoto1, 2, Yunyoung Hwang1, 3, Liyang Liao3,
Yoshichika Otani1, 3*Presenter
1
Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
2
Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
3
Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
Abstract
Magnetoelastic interaction is a fundamental property of magnetostrictive material. One important
effect is the magnetic resonance driven by surface acoustic waves (SAW), which causes
nonreciprocal SAW absorption in magnet films [1, 2, 3]. Particularly, nonreciprocity is the key
feature of rectification devices such as circulators and isolators. Ferrimagnet insulator Yttrium irongarnet (Y3Fe5O12, YIG) attracts much interest due to its relatively low magnetic damping and longrelaxation time [4, 5], which has great potential in microwave devices. However, the investigationof SAW driven magnetic resonance in YIG is limited by its low compatibility of YIG and SAW
devices. In this work, we demonstrate resonant surface acoustic wave absorption in an on-chip
YIG/SAW device fabricated by FIB technique. We present two SAW absorption features withdifferent symmetries about propagation wavevector, which indicates a unique unidirectional SAW
propagation for a board range of magnetic field directions. The large nonreciprocity in SAW
propagation direction in YIG offers a promising opportunity for high-efficient rf signal processing
technologies.
References[1] M. R. Daniel, Ferroacoustic interaction in yttrium iron garnet with Rayleigh waves. J. Appl.
Phys. 44, 1404 (1973).
[2] P. R. Emtage, Nonreciprocal attenuation of magnetoelastic surface waves. Phys. Rev. B 13,3063 (1976).
[3] M. R. Daniel, Experimental observation of nonreciprocal attenuation of surface waves inyttrium iron garnet. J. Phys. D: Appl. Phys. 48, 1732 (1977).
[4] V. Cherepanov, I. Kolokolovb, V. L’vov, The saga of YIG: spectra, thermodynamics,
interaction and relaxation of magnons in a complex magnet. Phys. Rep. 229, 81 (1993).
[5] A. A. Serga, A. V. Chumak, B. Hillebrands, YIG magnonics. J. Phys. D: Appl. Phys. 43,
264002 (2010).

Ideal Spin-Orbit-Free Dirac Semimetal RE8CoX3 (RE = rare earth
elements, X = Al, Ga, or In)
Manabu Sato1*, Juba Bouaziz2, Shuntaro Sumita1,3, Shingo Kobayashi3,
Ikuma Tateishi3, Stefan Blügel2, Akira Furusaki3, and Motoaki Hirayama1,3*Presenter
1
The University of Tokyo, Japan
2
Forschungszentrum Jülich, Germany
3
RIKEN, Japan

Abstract
Topological semimetals are a fascinating group of materials with degeneracies between
valence and conduction bands that exhibit intriguing electronic properties in the bulk and at
the surface [1]. Most of the typical topological semimetals such as the Weyl and nodal-line
semimetal phases have been found in real materials both in systems with negligible spin-orbit
coupling (spinless systems) as well as in systems with strong spin-orbit coupling (spinful
systems). However, no material realization of spinless Dirac semimetals has been discovered,in which the valence and conduction bands touch at a fourfold degenerate (without including
spin degeneracy) point.
In this study, we show from first-principles calculations that spin-orbit-free materials in the
RE8CoX3 (RE = rare earth elements, X = Al, Ga, or In) group are ideal spinless Diracsemimetals whose Fermi surfaces consist only of fourfold degenerate points. Furthermore, weinvestigate various topological phase transitions exhibited by the Dirac semimetal phase,
which is located at phase boundaries, using first-principles calculations and effective model
analysis. Lattice distortion or elemental substitutions change the system into characteristic
topological semimetallic phases including linked-nodal-line and ferromagnetic Weyl
semimetals.

References[1] N. P. Armitage, E. J. Mele, and A. Vishwanath, Rev. Mod. Phys. 90, 015001 (2018).

Cr-doping effects on the magneto-thermoelectric properties of
the antiferromagnetic Weyl semimetal Mn3Sn thin film
Yutaro Tsushima1*, Tomoya Higo1,2, Mihiro Asakura1, Shunihiro Kurosawa1,
Ryota Uesugi2, Satoru Nakatsuji1,2,3
1School of Science, University of Tokyo, Japan
ISSP, University of Tokyo, Japan
3
Johns Hopkins University, USA
2

In recent years, antiferromagnetic materials exhibiting large anomalous Hall and Nernst effects
have been discovered despite their vanishingly small magnetization [1,2]. These substances are
garnering attention as promising candidates for novel spintronic devices due to their ultrafast
dynamics and negligibly small demagnetizing field. One of the typical examples is theantiferromagnetic Weyl semimetal Mn3Sn, which is known to show large anomalous Nernst effect[3] as well as anomalous Hall effect [4] originating from Weyl points, and intensive research is
being conducted for the development of devices, including non-volatile memories and magneticallyrobust heat flux sensors [1,5]. Recently, studies on the control of transport properties of Mn3Sn by
Fermi level tuning have also attracted much attention, and the doping effects of 3d electrons in theanomalous Hall effect have been studied [6]. On the other hand, the contribution to the anomalous
Nernst effect, a probe sensitive to Berry curvature near the Fermi level, remains unexplored. In thisstudy, we focused on Cr-doped Mn3Sn to assess its magneto-thermoelectric responses and measured
the magneto-thermoelectric properties of Mn3Sn films with varying Cr compositions.
References[1] S. Nakatsuji and R. Arita, Annu. Rev. Condens. Mat. Phys. 13, 119 (2022).
[2] L. Šmejkal et al., Nat. Rev. Mater. 7, 482 (2022).
[3] M. Ikhlas, T. Tomita et al., Nat. Phys. 13, 1085 (2017).
[4] S. Nakatsuji, N. Kiyohara, and T. Higo, Nature 527, 212 (2015).
[5] T. Higo and S. Nakatsuji, JMMM 564, 170176 (2022).
[6] X. Chen et.al., arXiv:2107.00959 (2021); A. Low et.al., Phys. Rev. B 106, 144429 (2022).

Magnetic imaging by the anomalous Nernst effect using atomic
force microscopy:
N. Budai1*, H. Isshiki1, 2, A. Kobayashi1, R. Uesegi1, Z. Zhu1, T. Higo1, 2,3, S.
Nakatsuji1, 2, 3, 5 and Y. Otani1, 2, 4, 5
*Presenter
1
Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
2
CREST, Japan Science and Technology Agency (JST); Saitama, 332-0012, Japan.
3
Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
4
Trans-scale Quantum Science Institute, The University of Tokyo; Bunkyo-ku, Tokyo, 1130033, Japan.
5Center for Emergent Matter Science RIKEN, Wako, Saitama 51-0198, Japan
Mn3Sn has recently achieved wide attention since it exhibits anomalous Hall and Nernst effects(ANE) despite being an antiferromagnet. This can be explained by its non-collinear
antiferromagnetic spinorder [1]. Mn3Sn is a promising candidate for data storage or thermopile
devices for efficient energy-harvesting. Here, we show a high-resolution magnetic imaging
method which does not rely on any net magnetization and is therefore applicable on any material
exhibiting the ANE. The technique is based on atomic force microscopy (AFM) and the ANE.
By heating up the sample with an external heater a local vertical temperature gradient, ∇Tz, is
induced by the AFM-tip contact (see Figure below). Due to the magnetization dependence of
the ANE, given by
EANE = SANE · (m × ∇T),
the magnetization of the sample can be mapped accurately. In fact, we achieved an impressive
sub-100 nm spatial resolution on a Weyl ferromagnet (Co2MnGa) [2]. Furthermore, we could
show magnetic contrast in Permalloy [3] and Mn3Sn. By simulating the induced temperature
gradient, we were able to estimate the local ANE of the measured material. With this poster wewant to present our results on Co2MnGa and Mn3Sn.

Figure: Schematics of the magnetic imaging technique. The temperature of the sample is raised bya parallel heating wire. By tip-contact on the sample a vertical temperature gradient is induced which
creates the measurable ANE.

References[1] S. Nakatsuji et al., Nature 527, (2015)[2] N. Budai et al., Appl. Phys. Lett. 122, 102401 (2023)[3] H. Isshiki et al., Front. Phys. 11 (2023)

First-principles derivation of classical spin models based on thespin cluster expansion
Tatsuto. Hatanaka1*, Takuya. Nomoto2, Ryotaro. Arita2,3*Presenter
1
Department of Applied Physics, The University of Tokyo, Japan
2
Research Center for Advanced Science and Technology, University of Tokyo, Japan
3
RIKEN Center for Emergent Matter Science (CEMS), Japan
Abstract (up to 200 words)
The ab initio construction of effective spin models for real materials is a longstanding
problem. In particular, higher-order terms than the bilinear interactions are difficult toestimate directly with a conventional method, namely the local force method. By combining
the spin cluster expansion[1] and the disordered local moment method (SCE-DLM
scheme)[2], it is possible to expand a classical spin system's energy with arbitrary interactions
and calculate its parameters from the first-principles calculation. We calculated thebiquadratic interaction, which plays a crucial role in stabilizing non-coplanar spin textures foranti-ferromagnets[3,4]. Though the scheme was originally developed under the KKRformalism, we implemented the scheme using the Wannier orbitals from the DFT with theplane wave basis. In the presentation, we will discuss the results obtained by applying the
SCE-DLM scheme to 3d transition metals, which are typical magnetic materials, and compare
the results with those obtained by the conventional method.

References[1] R. Drautz and M. Fähnle, Phys. Rev. B 69, 104404[2] L. Szunyogh, L. Udvardi, J. Jackson, U. Nowak, and R. Chantrell, Phys. Rev. B 83,
024401[3] Takagi, H., Takagi, R., Minami, S. et al., Nat. Phys. 19, 961–968 (2023).
[4] Park, P., Cho, W., Kim, C. et al., Nat. Commun. 14, 8346 (2023).

Flux-periodic supercurrent oscillations in GaAs/InAs/Al
core/shell/halfshell nanowire Josephson junctions
P. Zellekens1,2*, R. Deacon1,3, M. Randle1,3, M. Lepsa3,4, D. Grützmacher3,4,
T. Schäpers3,4, K. Ishibashi1,2,3
1

RIKEN Center for Emergent Matter Science, 351-0198 Saitama, Japan
Quantum Effect Device Research Team, RIKEN, 351-0198 Saitama, Japan
3
Advanced Device Laboratory, RIKEN, 351-0198 Saitama, Japan
4
Peter Grünberg Institute, Forschungszentrum Jülich, 52428 Jülich, Germany
5
JARA-FIT, Fundamentals of Future Information Technology

2E-mail: patrick.zellekens@riken.jp

Mesoscopic nanowire Josephson junctions have been proposed as a potential building block for
topological systems. The state-of-the-art realization is based on the combination of a semiconductor
with strong spin-orbit interaction such as InAs or InSb with an epitaxially grown superconducting
shell. However, one of the main challenges is the creation of separate spin branches in the state
spectrum (“helical gap”) due to the strong in-plane field that is required to induce a sufficient
Zeeman splitting.
To overcome this, several other approaches have been proposed that try to limit the challenges
during the actual experiment by exploting more complex device layouts. One of them is based on
the so-called Little-Parks effect, whose most famous signature is the formation of supercurrent“lobes” separated by dissipative transport.
Even though signatures of this effect have already been observed in nanowires fully surrounded bya superconducting shell, many questions regarding the actual formation of the hybridized states andthe influence of the system dimensions still need to be addressed. Here, we use GaAs/InAs/Al
core/shell/halfshell nanowires due to the strong localization of the transport within the narrow band
gap semiconductor as a testbed to get more insight into this effect and to study the observed fluxperiodic oscillations.

Title: Precipitable Water Vapor Measurement using GNSS Datain the Atacama Desert for Millimeter and Submillimeter
Astronomical Observations
J. Sugiyama1*, H. Nishino2, 3, A. Kusaka1, 2, 4, 5
*Presenter
1
The University of Tokyo, Japan
2
Research Center for the Early Universe (RESCEU), Japan
3
Japan Synchrotron Radiation Research Institute (JASRI), Japan
4
Lawrence Berkeley National Laboratory, USA
5
Kavli Institute for the Physics and Mathematics of the Universe (WPI), Japan
Abstract (up to 200 words)
The precipitable water vapor (PWV) strongly affects the quality of data obtained frommillimeter- and submillimeter-wave astronomical observations [1], such as those for cosmic
microwave background (CMB) measurements. In this presentation, I will introduce the PWV
measurement method using Global Navigation Satellite System (GNSS).
Compared to other PWV measurement methods, GNSS instruments are robust in bad weather
conditions, have sufficient time resolution, and are less expensive. By demonstrating PWV
measurements with good accuracy using GNSS instruments in the Atacama Desert, whichhosts several CMB experiments [2-6], I will show that GNSS instruments are valuable tools
for PWV measurements for observing site evaluation and data analysis for ground-based
telescopes [7].

References[1] Radford S. J., Holdaway M. A., 1998. SPIE, pp 486 – 494[2] Swetz D. S., et al., 2011, The Astrophysical Journal Supplement Series, 194, 41[3] Kermish Z. D., et al., 2012, in Holland W. S., ed., SPIE Proceedings. SPIE
[4] Suzuki A., et al., 2016, Journal of Low Temperature Physics, 184, 805[5] Kusaka A., et al., 2018, Journal of Cosmology and Astroparticle Physics, 2018, 005[6] Ade P., et al., 2019, Journal of Cosmology and Astroparticle Physics, 2019, 056[7] Sugiyama J., et al., 2023, arXiv:2308.12632

Hollow Lattice Tensor Gauge Theories with Bosonic Matter
J.M. Cruz1,2*, P.A. McClarty3, P. Ribeiro1, M. Udagawa2, P. Bicudo1
1 CeFEMA-LaPMET, Portugal
2 Gakushuin University, Japan
3 Max Planck Institute for the Physics of Complex Systems, Germany

Higher rank gauge theories are generalizations of electromagnetism where, in addition to
charge conservation, there is also conservation of higher rank multipoles such as the total
dipole moment among other conservation laws. In this work we study the four dimensionallattice A tensor gauge theory coupled to bosonic matter which has second rank tensor electricand magnetic fields and charge conservation on individual planes. Analytical predictions wereobtained for the pure gauge case (no matter) where charge excitations are quadrupolar. For
strong coupling, we retrieve a volume law where the quadrupole potential grows quadraticallyin the distance between charges. For weak coupling we find an area law and a linear
quadrupolar potential. No phase transition was found between these regimes due to instanton
proliferation. With the inclusion of matter fields with charge p=2 a distinct phase arises. We
dubbed it the Higgs Phase in analogy with the rank-one U(1). At infinite gauge coupling thetheory reduces to the (3+1)D XY-plaquette model.

References[1] J.M. Cruz, P.A. McClarty, P. Ribeiro, M. Udagawa, P. Bicudo, “Hollow Lattice Tensor
Gauge Theories with Bosonic Matter” (in preparation).
[2] Seiberg, Nathan & Shao, Shu-Heng, SciPost Phys. 9, 046 (2020), “Exotic $U(1)$Symmetries, Duality, and Fractons in 3+1-Dimensional Quantum Field Theory”.
[3] D. Bulmash and M. Barkeshli, Phys. Rev. B 97 (23), 235112(2018), “The Higgs Mechanism in Higher-Rank Symmetric U(1)Gauge Theories”.

Nonlocally Detected Diffusive Orbital Current Generated via
Orbital Edelstein Effect
Gao Weiguang 1*, Hironari Isshiki1, Junyeon Kim2, and YoshiChika Otani1,2,3*Presenter
1
Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277–8581, Japan
2
Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
3
Trans-scale Quantum Science Institute, The University of Tokyo, Bunkyo-ku, Tokyo, 1130033, Japan
Abstract
The recently emerging field in spintronics focuses on the electron orbital angularmomentum (OAM) which could similarly function like the electron spin. The nonequilibrium
OAM accumulation was recently found to be generated via the interfacial orbital Edelsteineffect (OEE) [1,2] and the bulk orbital Hall effect (OHE) [3]. Importantly, these charge toorbital conversions require no spin-orbit interaction. In this study, we provide robust evidenceof both direct and inverse OEE in lateral transport structures, comprising orbital accumulation
generator/detector Al2O3/Cu interfaces and detector/injector ferromagnetic nanowires. Throughsystematical studies of separation distance and Cu thickness dependences, we reveal that theconversion satisfies the Onsager reciprocity relation and an orbital diffusion length exceeds 110
nm, indicating the presence of a lateral orbital transport channel at the Al2O3/Cu interface. Our
experiments lay the groundwork for future fine manipulation of OAM and establish afoundational understanding for the practical applications of spintronics.

References[1] Kim J, et al. Physical Review B, 2021, 103(2): L020407.
[2] Kim J, et al. Physical Review Materials, 2023, 7(11): L111401.
[3] Choi Y G, et al. Nature, 2023, 619(7968): 52-56.

Non-negative Matrix Factorization Analysis for Angle-Resolved
Photoemission Spectra of Graphene
M. Imamura* and K. Takahashi
Synchrotron Light Application Center, Saga University, Japan
Angle-resolved photoemission spectroscopy (ARPES) has been used as a useful tool in theinvestigation for the direct observation of the electronic states in momentum space. In recent
years, as the performance of light sources and equipment has improved, the volume ofobtained data through the measurement has rapidly increased. Machine learning has been
applied as a solution to increment of the data. In this study, non-negative matrix factorization(NMF) was applied to the ARPES dataset of graphene grown on SiC substrates. The dataset
consists of spectra measured for graphene near the Dirac cone with the synchrotron radiation
at 400 different positions on the substrate. Each spectra reflects the local electronic structureof measured region. The experimentally obtained spectra were decomposed into several
features and well reproduced by the NMF. The basis and activation vectors obtained by NMF
reflect changes in the spectral shape due to deviations in the number of layers and grownangles. In addition, the distribution of the graphene on the substrate were visualized through aclassification by activation vectors obtained by NMF. These results indicate that NMF is aneffective tool for the feature detection and the analysis for the large number of ARPES spectra.

Kazutoshi Takahashi
Among group-V elemental two-dimensional materials, a heavier Bi contributes to a stronger spinorbit coupling (SOC), resulting in a larger bandgap opening of the non-trivial phase. Interaction
between the two-dimensional layer and the substrate is vital for tuning the material properties throughsymmetry, electronic coupling, and strain. Recently, a flat honeycomb structure of bismuthene wasdistinguished on Ag(111). The flat bismuthene exhibit a (2×2) superstructure with Bi atoms located at
the hollow sites of Ag(111), indicating that the distance between two Bi atoms on Ag(111) is 3.34 Å,
which is 108.7% of the interatomic distance in the buckled Bi(111) layer. In this work, twodimensional band dispersion of (2×2) superstructure with Bi grown on Ag(111), which has been urged
as an ultraflat hexagonal bismuthene, is investigated using angle-resolved photoemission spectroscopy_(ARPES). A band dispersing to the high binding energy side with tops at the first and second K points
appears on the (2×2)-Bi surface. The observed dispersion is consistent with the calculated band with
pxy character in ultraflat-Bi of the (2×2) structure on 3 ML Ag(111) layers.

Thermal fluctuation induced anisotropic topological Hall effect inpyrochlore-type Eu2Mo2O7
H. Fukuda1*, K. Ueda1, C. Terakura2,
Y. Kaneko2, M. Hirschberger1,2, and Y. Tokura1, 2, 3
1

*Presenter, email: fukuda-hikaru527@g.ecc.u-tokyo.ac.jp
Department of Applied Physics, The University of Tokyo, Japan
2
RIKEN Center for Emergent Matter Science (CEMS), Japan
3
Tokyo College, The University of Tokyo, Japan

It has been demonstrated that topological spin textures play an important role in the quantum
electromagnetic properties. For example, when the conduction electron is coupled to a noncoplanar spin texture, its wave function obtains the Berry phase proportional to the scalar spinchirality 𝜒ijk = 𝑆i ⋅ (𝑆j × 𝑆k ). Then the emergent Berry curvature field causes unconventional
Hall effect (topological Hall effect). So far, the topological Hall effect has been mainly studied
for pyrochlore A2B2O7 compounds (A-site: f electron, B-site: d electron) [1][2]. But thecoexistence of conduction electrons and localized moments makes the system complicated to
explore the topological Hall effect.
Here, we report on a new topological Hall system, pyrochlore-type Eu2Mo2O7. Because Eu3+
(J = 0) is non-magnetic, we can focus on the magnetic structure of Mo-4d electrons only. Thissystem shows a field-anisotropic Hall effect, although all other physical properties such as
resistivity or magnetization are isotropic. Thisanisotropy persists even above the Curie-Weisstemperature. Our comprehensive theoretical
study of Heisenberg model on the pyrochlore
lattice suggests that this anisotropy arises fromtopological Hall effect induced by thermal
fluctuation. Our findings may pave the way forthe topological Hall effect devices working ina broad temperature range, exceeding themagnetic transition temperature.

References[1] Y. Taguchi, Y Oohara, H. Yoshizawa, N. Nagaosa, and Y. Tokura, Science 291, 5513 (2001).
[2] Y. Machida, S. Nakatsuji, Y. Maeno, T. Tayama, T. Sakakibara, and S. Onoda, Phys. Rev.
Lett 98, 057203 (2007).

Title: Theoretical studies of the electric field induced thermal Hall
effect in the quantum dimer magnets XCuCl3 (X = Tl, K)
N. Esaki1*, Y. Akagi1 and H. Katsura1*Presenter
1Department of Physics, The University of Tokyo, Japan
Abstract
The thermal Hall effect in magnets has attracted increasing attention in recent years as a
powerful probe of elementary excitations in solids and their nontrivial band topology. In
quantum dimer magnets, where neighboring two S=1/2 spins form a dimer by the strong
antiferromagnetic interaction, their elementary excitations are bosonic quasiparticle triplons.
However, the thermal Hall effect of triplons has yet to be detected [1] although its candidate
material has been proposed theoretically [2]. For this reason, we should seek other candidate
materials exhibiting the thermal Hall effect of triplons.
In this work, we theoretically propose the electric field induced thermal Hall effect of triplonsin the quantum dimer magnets XCuCl3 (X = Tl, K) [3], which exhibit ferroelectricity in the
Bose-Einstein condensation phase of triplons. The interplay between ferroelectricity andmagnetism in these materials leads to the magnetoelectric effect, i.e., an electric-field induced
Dzyaloshinskii-Moriya (DM) interaction on the same dimer. We argue that this DM
interaction breaks the symmetry of the system without an electric field and gives rise to thethermal Hall effect, which can be detected in realizable external fields. We also show that thethermal Hall effect can be controlled by an electric field (Fig. 1).

(a)

(b)

Fig. 1: Electric field dependence of the thermal Hall conductivity κzx.
(a) |κzx| is enhanced by increasing the strength of the electric field |E|.
(b) Electric field in the x-y plane changes the sign of κzx.
References[1] S. Suetsugu et al., Phys. Rev. B 105, 024415 (2022).
[2] J. Romhányi, K. Penc, and R. Ganesh, Nat. Commun. 6, 6805 (2015).
[3] N. Esaki, Y. Akagi, and H. Katsura, arXiv: 2309.12812.

Title: Fundamental Laws of Chiral Band Crossings
K. Alpin1, M. M. Hirschmann1,2*,N. Heinsdorf1,3, A. Leonhardt1, W. Y. Yau1,4,
X. Wu1,5, and A. P. Schnyder1*Presenter
1
Max Planck Institute for Solid State Research, Germany
2
RIKEN Center for Emergent Matter Science, Japan3
Department of Physics and Astronomy & Stewart Blusson Quantum Matter Institute,
University of British Columbia, Canada
4
Max Planck Institute of Molecular Cell Biology and Genetics, Germany
5
Institute for Theoretical Physics, Chinese Academy of Sciences, China

The number of surface states as well as the electric response of Weyl semimetals isdetermined to a large extent by the Chern number of the Weyl points, a property also referred
to as their chirality. It is known [1,2] that rotation eigenvalues affect the value of the chirality.
We show that the previous works are applications of a local constraint [3], relating the Chern
number with the exchange of rotation eigenvalues. We find that it holds for arbitrary
combinations of symmetries as well as for chiral crossings comprising more than two bands.
Using this constraint, we explain the chiralities of quadruple Weyl points, double Weyl points
on two-fold rotation axes, and discuss the emergence of a Chern number 5 band within certain
fourfold point crossings. Furthermore, with a global constraint, stemming from the periodicityof the Brillouin zone, we can identify space groups with enforced topological nodal planes.

References[1] C. Fang, et al., Phys. Rev. Lett. 108, 266802 (2012)[2] S. S. Tsirkin, et al., Phys. Rev. B 96, 045102 (2017)[3] K. Alpin et al., Phys. Rev. Research 5, 043165 (2023)

Title: No-Go Theorem from Eigenstate Thermalization
Hypothesis about Work Extractability in Locally Interacting
Systems

A. Hokkyo1*, M. Ueda1, 2, 3
*Presenter
1
Dept. of Phys., the Univ. of Tokyo, Tokyo, Japan
2
Institute for Physics of Intelligence, the Univ. of Tokyo, Tokyo, Japan
3
RIKEN Center for Emergent Matter Science, Japan
Abstract (up to 200 words)
There exist two independent characterizations of thermal equilibrium states in quantum
theory: passivity [1][2] and consistency with statistical mechanics. The former aligns with
Planck's principle, representing a formulation of the second law of thermodynamics inmacroscopic thermodynamics. It posits that no work can be extracted in an adiabatic cycle.
The latter suggests that the thermal equilibrium state has the same expectation values ofthermal observables as the microcanonical state. The hypothesis that energy eigenstates
exhibit this property is termed the eigenstate thermalization hypothesis (ETH) [3][4]. While
extensive research has been conducted on each of these properties, the relationship between
them remains unclear. This lack of clarity becomes a crucial issue when exploring
thermodynamic properties beyond equilibration in quantum many-body systems.
In this presentation, I will discuss the relationship between the maximum extractable work
(ergotropy) in many-body systems and the properties of thermal equilibrium as expressed
through observables. We demonstrate that ergotropy is constrained by the athermality of theinitial state and the reduction of entanglement entropy resulting from quantum operations. Ourfindings thus indicate that the ETH prohibits work extraction from energy eigenstates during
time evolution induced by local observables in 1D systems.
References[1] W. Pusz and S. L. Woronowicz, Comm. Math. Phys. 58, 273 (1978).
[2] A. Lenard, J. Stat. Phys. 19, 575 (1978).
[3] J. M. Deutsch, Phys. Rev. A 43, 2046 (1991).
[4] M. Srednicki, Phys. Rev. E 50, 888 (1994).

Title: Development of Torsion Pendulums and Readout Optics for
Gravity Gradient Observation
Y. Oshima1*, S. Takano1, C. P. Ooi1, M. Cao2, P. W. F. Forsyth1,
Y. Michimura3, 4, K. Komori4 and M. Ando1, 4*Presenter
1
Department of Physics, University of Tokyo2
Beijing Normal University3
California Institute of Technology
4
RESCEU, University of Tokyo
Abstract
Torsion-Bar Antenna (TOBA) is a low-frequency gravity gradient detector using torsion
pendulums [1]. Gravity gradient fluctuation is measured as the differential rotation of two
horizontally suspended bars. The resonant frequency of torsional motion is low (~1 mHz)
therefore TOBA has good design sensitivity, specifically 10-19 /√Hz between 0.1-10 Hz with
10 m-scale pendulums. TOBA can be used for gravitational-wave observation [1] andearthquake early warning [2]. A prototype detector Phase-III TOBA with 35 cm-scalependulums at cryogenic temperature is under development to demonstrate noise reduction [3].
The target sensitivity is set to 10-15 /√Hz at 0.1 Hz. Currently we are developing cryogenic
torsion pendulums made of silicon and Fabry-Pérot cavities to detect the differential rotationof pendulums.

Fig 1: The schematic of torsion pendulums and Fabry-Pérot cavity

References[1] M. Ando et al., Phys. Rev. Lett. 105, 161101 (2010)[2] J. Harms et al., Phys. Rev. D 88, 122003 (2013)[3] T. Shimoda et al., International Journal of Modern Physics D 29, 1940003 (2020)

Development of Quantum Sensing under High Pressure:
Visualization of Pressure and Magnetic Field
Ryotaro Suda1*, Kento Sasaki1, Kensuke Kobayashi1, Kenshin Uriu2, Misaki
Sasaki2, Mari Einaga2 and Katsuya Shimizu2
1
2

Univ. of Tokyo, JapanKYOKUGEN, Osaka Univ., Japan

Abstract
NV centers in diamonds act as quantum sensors, detecting magnetic fields, pressure, andtemperature with high sensitivity through optical detection magnetic resonance (ODMR)
methods. The ability to quantitatively image magnetic fields make this technology promisingfor condensed matter physics experiments. The measurement using nanometer-sized is simple
in terms of their availability and can be directly sprayed near the sample for precise
measurement.
NV centers are currently being used to measure high-pressure magnetic fields in the GPa region[1]. Therefore, by adding nanodiamonds with NV centers to the sample chamber of a diamondanvil cell (DAC) for pressurization, it is expected to image the magnetic field and pressure in
the vicinity of the material. This will be useful for observing changes in magnetism during highpressure phase transitions and the Meissner effect in pressure-induced superconductivity.
In this study, imaging measurements of pressure and magnetic field were attempted using
nanodiamonds scattered inside a sample chamber at 10 to 20 GPa. In addition, we analyze themeasured signals considering the bias of the stress distribution and compare the results with thestress measurements obtained from the shift of the fluorescence wavelength of the ruby in thesample chamber.
References[1] K. Y. Yip et al., Science 366, 1355 (2019).

Calculation method for the coherence length at low temperatures
H. Matsunaga 1*, R. Oiwa 2, T. Nomoto 3, and R. Arita 2, 3
1

Department of Applied Physics, The University of Tokyo, Hongo, Tokyo, 113-8656,
Japan
2
Center for Emergent Matter Science, RIKEN, Wako, Saitama, 351-0198, Japan
3
Research Center for Advanced Science and Technology, The University of Tokyo,
Komaba, Tokyo, 153-8904, Japan
Abstract
The coherence length is a macroscopic length that characterizes superconductivity andis defined by the Ginzburg-Landau (GL) theory. Recently, a method based on the GL
theory has been proposed to calculate the coherence length near the transition temperature.
This method utilizes the value of the gap function (∆𝑞 ) for Cooper pairs with finite
momentum (𝑞) [1]. On the other hand, calculating the coherence length directly at low
temperatures has been challenging, and it has been determined only through fitting.
In this study, we found that ∆𝑞 is an increasing function of 𝑞 at low temperatures.
This is why the coherence length is calculated as the imaginary length using theconventional GL theory (Fig. 1). To overcome this problem, we extended the GL theory,developing a method for calculating the coherence length at low temperatures (Fig 1). In

References[1] N. Witt et al., arXiv:2310.09063.

𝜉/𝑎0

this poster presentation, we will discuss the details of the extended GL theory and our
methodology for calculating the coherence length at low temperatures.

𝑘𝐵 𝑇/𝑡Fig. 1 Temperature dependence of the coherence length 𝜉
calculated in a one-dimensional attractive Hubbard model.
Here, 𝑡 is the nearest neighbor hopping, 𝑘𝐵 𝑇 is thetemperature, and 𝑎0 is the lattice constant of the system.

Search for superconductivity in La-N-H by evolutionary
algorithm, neural network potential, and density functional
theoryT. Ishikawa1* and S. Tsuneyuki1
1

Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan
Lanthanum hydride (La-H) has attracted much attention as a potential candidate for roomtemperature superconductivity since the discovery of the superconductivity at 260 K atpressure of 170 GPa [1,2]. The superconducting critical temperature Tc was reported to befurther increased to 556 K, which has been considered to be caused by reaction of La-H withother materials [3], and the information on ternary or multinary hydrides based on La is
crucial for the understanding of the “hot superconductivity”.
Assuming that La-H is reacted with hydrogen-source NH3BH3, we exploredthermodynamically stable and superconducting phases in the La-N-H system at 20 GPa. We
quickly optimized a few thousand structures created by evolutionary algorithm [4] using
universal neural network potentials on Matlantis [5], extracted only a few ten structures
emerging near the formation-energy convex hull, and optimized them using the density
functional theory calculations. For the stable compounds obtained by repeating this process,we calculated Tc using the Allen-Dynes formula and found a new superconducting material,
La2NH2, showing Tc of 14.4 K [6]. The Tc value is far from hot superconductivity and further
studies are required to verify it. This work is supported by ENEOS Corporation.
References[1] M. Somayazulu et al., Phys. Rev. Lett. 122, 027001 (2019).
[2] A. P. Drozdov et al., Nature 569, 528 (2019).
[3] A. D. Grockowiak et al., Front. Electron. Mater. 2, 837651 (2022).
[4] T. Ishikawa and T. Miyake, Phys. Rev. B 101, 214106 (2020).
[5] Matlantis (https://matlantis.com/), software as a service style material discovery tool.
[6] T. Ishikawa, Y. Tanaka, and S. Tsuneyuki, arXiv:2312.01290 (2023).

Energy Flow during Relaxation in an Electron–Phonon Systemwith Multiple Modes: A Nonequilibrium Green’s Function Study
Ken Inayoshi1*, Akihisa Koga1, and Yuta Murakami2*Presenter
1
Department of Physics, Tokyo Institute of Technology
2Center for Emergent Matter Science, RIKEN
The relaxation dynamics of correlated electron systems is one of the important phenomena innonequilibrium condensed matter physics. Although approximate methods such as thetemperature model (TM) [1] and Boltzmann equation (BE) [2] have been widely used toanalyze the relaxation, it remains unclear whether the relevant processes can be properly
explained using them. Therefore, it is crucial to identify the necessary elements to explain therelaxation dynamics using the microscopic approach, i.e., the nonequilibrium Green’s
function method [3].
In this study, we introduce an extended Holstein model where electrons couple to two
phonon modes, and study the relaxation dynamics using nonequilibrium dynamical meanfield theory (DMFT). To clarify the microscopic mechanism of the energy flow, we compare
the full energy flow calculated with nonequilibrium DMFT and the approximated energy flow
calculated with approximations employed in the TM and BE. In the weak electron-phonon
coupling regime, we confirm that the mechanism of the energy flow is well explained in termsof the effective temperatures as in the TM. On the other hand, in the stronger electron-phonon
coupling regime, we find that the effects beyond the TM and BE are necessary to capture thebehavior of the full energy flow [4].
References[1] L. Waldecker, et al., Phys. Rev. X 6, 021003 (2016).
[2] S. Ono, Phys. Rev. B 97, 054310 (2018).
[3] A. F. Kemper, O. Abdurazakov, and J. K. Freericks, Phys. Rev. X 8, 041009 (2018).
[4] K. Inayoshi, A. Koga, and Y. Murakami, J. Phys. Soc. Jpn. 92, 124001 (2023).

Topological interface states of magnetic half-Heusler materials
Tonghua Yu1*, Ryotaro Arita2,3, and Motoaki Hirayama1,3
1Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
2Research Center for Advanced Science and Technology, University of Tokyo, Tokyo 153-8904, Japan
3RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, 351-0198, Japan

Half-Heusler materials are a well-known platform for engineering topological and otherelectronic properties, leveraging their compositional and structural richness. In thisstudy, we elucidate the emergence of topological interface states in magnetic halfHeusler compounds through the iterative Green's function approach. Our primary focus
centers on the rare-earth-based half-Heusler compound LuPtBi, which was
experimentally reported to exhibit topological surface states. By interfacing it with themagnetic trivial half-Heusler GdNiSb, we demonstrate the persistence of topologicalboundary states at the interface, further accompanied by a fairly large quantum
anomalous Hall gap around tens of meV. Considering the superconducting behavior in
LuPtBi, we will additionally discuss the intriguing prospects of topologicalsuperconductivity within this LuPtBi-GdNiSb interface. Other candidate systems will
also be introduced.

Title: Microscopically-derived quantum master equation for aboundary-driven Hubbard model and its application to nonlinear
thermoelectric effect
H. Ushihara1*, K. Takasan1, and N. Tsuji1, 2*Presenter
1
Department of Physics, University of Tokyo, Japan
2
RIKEN Center for Emergent Matter Science, JapanGK SL)/U
hJ N i (local
Particle
NE SS current

Abstract (up to 200 words)
Boundary-driven systems, systems coupled to two external baths at their ends, are good
platforms for studying nonequilibrium states and transport phenomena. One way to describe
quantum systems in contact with external degrees of freedom is to use quantum masterequations in the theory of open quantum systems [1]. Quantum master equations are wellunderstood for small open systems, such as atoms or molecules coupled to environments.
However, it has been claimed that the established equations are not directly applicable to open
many-body systems or transport phenomena [2].
3.0e− 42.0e− 4In this study, we microscopically derive a1.0e− 4
quantum master equation for a boundary-driven
0.0e− 4
fermionic Hubbard model, and numerically verify− 1.0e− 4
its applicability to transport phenomena [3]. Weµ/ U = 0− 2.0e− 4apply the derived equation to the thermoelectricµ/ U = 0.1− 3.0e− 4µ/ U = 0.5
effect and find a nonlinear sign-reversal behavior
0.0
0.2
0.4
0.6
0.8
through numerical calculations (Fig. 1). We also−β
T −T
= ββdifference
Temperature
T +T+βgive a physical interpretation of the nonlinear
behavior based on the derived expression of the Figure 1: Dependence of steady particle currents
on temperature differnece of the two baths. Here,equation.
(L)

(R )

(R )

(L)

(L)

(R )

(R )

(L)

μ and U denote the chemical potential and theon-site interaction, respectively.

References[1] H.-P. Breuer and F. Petruccione, The Theory of Open Quantum Systems (Oxford
University Press, 2007).
[2] H. Wichterich, M. J. Henrich, H.-P. Breuer, J. Gemmer, and M. Michel, Phys. Rev. E 76,
031115 (2007).
[3] H. Ushihara, K. Takasan, and N. Tsuji, in preparation.

Octupole polarization switching in Mn3Sn probed bymagnetoresistance through magnetic tunnel junction withdifferent sizes
R. Kondo1*, M. Yunokizaki1, H. Idzuchi1,2, K. Inukai3, K. Tanaka1,
S. Sakamoto2, T. Higo1,2,4, S. Miwa2,4,5 and S. Nakatsuji1,2,4,5,6*Presenter
1
Dept. of Phys. Univ. of Tokyo, Japan 2ISSP Univ. of Tokyo, Japan 3JSR Corp., Japan
4
JST-CREST, Japan 5TSQS Univ. of Tokyo, Japan 6Johns Hopkins Univ., USA
Antiferromagnetic spintronics has attracted attention from both the fundamental physics
viewpoint and its potential for applications [1,2]. The tunnel magnetoresistance (TMR) effectin a magnetic tunnel junction (MTJ) was difficult to realize with antiferromagnets though sometheoretical attempts had been made [3]. Recently, however, the TMR effect was observed with
noncolinear antiferromagnets Mn3Sn [4] and Mn3Pt [5]. Then, the magnetic order of Mn3Sn ischaracterized by the cluster magnetic octupole moments. In
the Mn3Sn-MTJ, the resistance change corresponds to theswitching of the cluster magnetic octupoles [4]. The
switching process of the sub-micron scale dot can be
examined by the anomalous Hall effect induced by shunting
current through adjacent Hall bar, or using MTJ structure.
So far, the former approach has been used with different
sizes of the junctions [6].
We examined how the junction size of Mn3Sn-MTJs
affects the octupole polarization switching process using
several Fe/MgO/Mn3Sn MTJ devices with different
junction diameters Φ. The TMR effect was clearly observed
down to Φ = 500 nm (Figure). As Φ increases, the switching Figure TMR effect ofFe/MgO/Mn3Sn MTJ
field approaches a constant value, and the switchingwith Φ = 500 nm at
becomes more gradual. Interestingly, this can be explained
300 K.
by the grain structure of the polycrystalline Mn3Sn.
Arrows show sweep
directions ofout-of-plane magnetic
field.

References[1] T. Jungwirth et al., Nat. Nanotechnol. 11, 231 (2016).
[2] S. Nakatsuji and R. Arita, Annu. Rev. Condens. Matter Phys. 13, 119 (2022).
[3] D.-F. Shao et al., Nat. Commun. 12, 7061 (2021).
[4] X. Chen, T. Higo, K. Tanaka et al., Nature 613, 490 (2023).
[5] P. Qin et al., Nature 613, 485 (2023).
[6] Y. Sato et al., Appl. Phys. Lett. 122, 122404 (2023).

Dynamic control of spin-wave by electric field in rare-earth ironfunctional oxide thin films
EMK Ikball Ahamed1*, Md Shamim Sarker2, Hiroyasu Yamahara2, Munetoshi
Seki1 and Hitoshi Tabata1, 2
1
2

Department of Electrical Engineering and Information Systems, The University of Tokyo, Japan
Department of Bioengineering, The University of Tokyo, JapanIn Rare-earth Iron Garnet (RIG) thin films, both spin and dipole coexistence are expected bybreaking the spatial inversion symmetry in tilted strained structure at the nanoscale [1].
Symmetry broken RIG thin films can be achieved by controlling the epitaxial strain. This study
aims to facilitate electric field-controlled spin-wave propagation in symmetry broken RIG thinfilms. Using comb-shaped interdigital metal electrodes, we applied an in-plane electric field
and investigated the electric field-controlled spin-wave propagation. We fabricated 100-120nm
Lu3Fe5O12 thin films on partial lattice mismatched (∼-0.88%) Ga3Gd5O12 substrates using thepulsed laser deposition technique. Subsequently, using photolithography and DC sputtering
techniques, we fabricated a pair of Au co-planner waveguides and Pt interdigital electrodes(Fig.1(a,b)). We measured spin-wave propagation by microwave technique using a Vector
Network Analyzer (Fig.1(c)). The spin-wave transmission spectra characteristics indicate asignificant right shift with the application of the electric field and completely turns back after
removing the field. This phenomenon may be attributed to spin–orbit coupling as well as the
spin-momentum locking in the ferromagnet/heavy-metal interface originating from the
Dzyaloshinskii–Moriya interaction [2]. This dynamic E-field controlled energy-efficient andheatless spin-wave device can be demonstrated as an alternative to conventional field effectswitching devices.

This research was supported by Institute for AI and Beyond for the University of Tokyo, JST, CREST Grant Number JPMJCR22O2,
Japan, AMED under Grant Number JP22zf0127006, JSPS KAKENHI Grant Number JP20H05651, JP22K18804, JP23H04099.

References[1] H. Yamahara. et al., Commun. Mater. 2, 95 (2021)[2] Titiksha Srivastava, et. al., Nano Lett., 18, 8, (2018)

Nanoscale imaging of magnetic texture dynamics by ultrafast
Lorentz transmission electron microscopy
D. Han1*, T. Shimojima2, A. Nakamura2, F. S. Yasin2, X. Yu2, K. Karube2, Y.
Taguchi2, Y. Tokura1, 2, 3, and K. Ishizaka1, 2, 4
*Presenter
1
Department of Applied Physics, The University of Tokyo, Japan
2
RIKEN Center for Emerging Matter Science (CEMS), Japan
3
Tokyo College, The University of Tokyo, Japan
4
Quantum-Phase Electronics Center, The University of Tokyo, Japan
Abstract
Ultrafast manipulation of nanoscale magnetic textures holds great promise for achieving
GHz-THz operation in spintronic devices. To explore this potential, it is essential to study the
dynamics of such magnetic nanotextures on ultrafast timescale [1]. Ultrafast transmission
electron microscopy (UTEM), which combines pump-probe method and electron microscopy,
emerges as a powerful technique due to its high spatiotemporal resolution [2]. Additionally,time-resolved Lorentz transmission electron microscopy (LTEM) measurement allows us toinvestigate ultrafast magnetic dynamics.
In this presentation, we introduce a recently developed ultrafast LTEM system at RIKEN
and demonstrate its capability for ultrafast nanoscale imaging with nm × ns resolution. As an
example, we performed UTEM measurements on pulse laser-induced magnetization dynamics
in helical Co9Zn9Mn2. Our observations revealed the demagnetization process followed by therecovery of the helical structure within the nanosecond to microsecond timescale.
Furthermore, we extended UTEM to track nm × ns current-induced magnetic domain wall
dynamics. By applying nanosecond pulsed current at current density below 1 × 1010 A/m2 on
ferromagnetic (Fe0.63Ni0.3Pd0.07)3P, we observed domain wall dynamics in which pinningpotential plays an important role. These results highlight the versatility and capability of
UTEM for studying photo- and current-induced dynamics in nanoscale magnetic textures.
References[1] J.-Y. Bigot and M. Vomir, Annalen der Physik 525, 2-30 (2013).
[2] T. Shimojima et al., Microscopy 72, 287-298 (2023).

Roll-to-Roll Printing of Anomalous Nernst Thermopiles for
Perpendicular Heat Flux Sensing
Hirokazu Tanaka1,4*, Tomoya Higo2-4, Ryota Uesugi3, Kazuto Yamagata1,4,
Yosuke Nakanishi1,4, Hironobu Machinaga1,4 and Satoru Nakatsuji2-6
1

Nitto Denko Corporation, Japan
Department of Physics, The University of Tokyo, Japan
3
Institute for Solid State Physics, The University of Tokyo, Japan
4
Laboratory for Magnetic and Electronic Properties at Interface, The University of Tokyo,
Japan
5
Trans-scale Quantum Science Institute, The University of Tokyo, Japan
6
IQM, Dept. of Physics and Astronomy, Johns Hopkins University, USA
2

The anomalous Nernst effect (ANE) converts heat flux perpendicular to the plane into
electricity, in sharp contrast with the Seebeck effect (SE), enabling mass production, large area,and flexibility of its devices through ordinary thin-film fabrication techniques[1,2]. Heat flux
sensors, one of the most promising applications of ANE[3-5], are powerful devices forevaluating heat flow and can lead to energy savings through efficient thermal management.
Moreover, the development of various topological magnets [6,7] exhibiting the giant ANE has
led to practical applications of ANE-type heat flux sensors. In reality, however, SE caused by
the in-plane heat flux is always superimposed on the measurement signal, making it difficult toevaluate the perpendicular heat flux.
In this study[8], we demonstrate a ANE-based flexible heat flux sensor that directly andselectively detects the perpendicular heat flux, where the Seebeck coefficients of the topologicalmagnet Fe-Ga and electrode material in the thermopile circuit are adjusted to be nearly
equal. Additionally, the SE-free sensor is fabricated by a simplified process designed for rollto-roll sputtering systems. Our demonstration of the direct perpendicular heat flux sensing
fabricated by mass-producible sputtering methods paves the way for practical applications of
ANE-type flexible thermoelectric devices.
References[1] Y. Sakuraba, Scr. Mater. 29, 111 (2016).
[2] M. Mizuguchi, S. Nakatsuji, Sci. Technol. Adv. Mater. 2019, 20, 262.
[3] W. Zhou and Y. Sakuraba, Appl. Phys. Express 2020 13, 043001.
[4] T. Higo et. al., Adv. Funct. Mater. 2021 31, 2008971.
[5] K. Uchida et.al., Appl. Phys. Lett. 2021 118, 140504.
[6] S. Nakatsuji and R. Arita, Annu. Rev. Condens. Matter Phys. 2022 13, 119.
[7] A. Sakai et al., Nature 2020 581, 53.
[8] H.Tanaka, T. Higo et.al., Adv. Mater. 2023 35, 2303416.

Giant anomalous Nernst effect in the epitaxial andpolycrystalline films of the Weyl ferromagnet Co2MnGa
R. Uesugi1*, T. Higo1,2, and S. Nakatsuji1,2,3,4,5
1

Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
3
Trans-scale Quantum Science Institute, The University of Tokyo, Bunkyo-ku, Tokyo 1130033, Japan
4
Institute for Quantum Matter Department of Physics and Astronomy, Johns Hopkins
University, Baltimore, Maryland 21218, USA
5
Canadian Institute for Advanced Research, Toronto, M5G 1Z7, ON, Canada
2

Recent discoveries of topological magnets have opened up diverse spintronic applicationsof their large responses beyond magnetization scaling observed in conventional
ferromagnets[1]. A prominent example is the anomalous Nernst effect (ANE), a transverse
magneto-thermoelectric phenomenon that produces an electromotive force orthogonal to theheat flux and magnetization. Unlike the Seebeck effect generating an electromotive force
parallel to the heat flux, transverse thermoelectric properties of ANE well fit in the lateralconfigurations of devices suitable for conventional thin-film fabrication processes[1-4]. Thisfeature enables distinct device applications through a simplified fabrication process, reduced
production cost, extensive area coverage, and enhanced flexibility[5]. In this study, we
focused on the Weyl ferromagnet Co2MnGa showing the largest ANE of −8 μV/K at room
temperature in its bulk form[6]. We have fabricated epitaxial films of the Co2MnGa on MgOsubstrates with the giant ANE of −5.5 μV/K originating from an atomically controllable
topological band structure. Moreover, we have also worked on the preparation ofpolycrystalline thin films suitable for mass production, and succeeded in fabricating a filmwith the largest ANE of −5.4 μV/K among thin films on amorphous templates[7]. Our works
lay the foundation for the future advancement of practical lateral magneto-thermoelectric
devices.

References[1] S. Nakatsuji and R. Arita, Annu. Rev. Condens. Matter Phys. 13, 119 (2022).
[2] M. Mizuguchi and S. Nakatsuji, Sci. Technol. Adv. Mater. 20, 262 (2019).
[3] Y. Sakuraba, Scr. Mater. 111, 29 (2016).
[4] K. Uchida and J. P. Heremans, Joule 6, 2240 (2022).
[5] H. Tanaka†, T. Higo†, R. Uesugi, et al., Adv. Mater. (2023).†[6] A. Sakai et al., Nat. Phys. 14, 1119 (2018); L. Xu et al., PRB 101, 180404 (2020).
[7] R. Uesugi, T. Higo, and S. Nakatsuji, Appl. Phys. Lett. 123, 252401 (2023).

Observation of magnetization process in artificial honeycomb spin
ice through tunnel magnetoresistance effect
H. Kubota1*, S. Tsunegi1, K. Yakushiji1, T. Taniguchi1, S. Tamaru1, T.
Yamamoto1, A. Sugihara1, R. Matsuura2, H. Nomura2,3,4, T. Isokawa5, Y.
Suzuki1,2,3*Presenter
1
AIST, Japan
2
Osaka University
3
CSRN-Osaka, country
4
Tohoku University, SRIS
5
Hyogo Prefecture University
Artificial spin ice (ASI) exhibits emergent dynamics [1], which can be applied to potential
applications such as a magnonic device [2] or physical reservoir computing [3, 4]. In theprevious experiments, the ASIs’ magnetization process was measured slowly by spectroscopic
methods [1, 5], causing low precision of magnetization switching properties in the individual
cells and their coupling. In this study, we fabricated ASIs by patterning magnetic tunnel
junction (MTJ) films so that magnetization process of the individual cells can be measured
precisely by magnetoresistance (MR) measurement. The MTJs had a FeB (15 nm) free layer on
a CoFeB /MgO film stack, which was microfabricated into 150-nm-wide and 800-nm-longstadium shape cells arranged in honeycomb structures [6] with distances between the nearest
vertexes of 1-2 µm. The ASIs consisted of 72 cells, in which 62 cells’ MR curves were
measured repeatedly at room temperature. The observed hysteresis loops were well
reproducible, which showed large MR ratios of 130-150% and average switching fields of 230310 Oe with standard variations of 20-40 Oe, depending on cell arrangements. The
magnetostatic coupling, evaluated quantitatively from the difference of the minor MR loops
measured after saturated in opposite directions, increased with decreasing the distance.
References[1] R. F. Wang, C. Nisoli, R. S. Freitas, J. Li, W. McConville, B. J. Cooley, M. S. Lund, N.
Samarth, C. Leighton, V. H. Crespi and P. Schiffer,Nature, 439 (2006) 303.
[2] S. Gliga, A. Kakay, R. Hertel and O. G. Heinonen,Phys Rev Lett, 110 (2013) 117205.
[3] J. C. Gartside, K. D. Stenning, A. Vanstone, H. H. Holder, D. M. Arroo, T. Dion, F. Caravelli,
H. Kurebayashi and W. R. Branford,Nat Nanotechnol, 17 (2022) 460.
[4] K. Hon, Y. Kuwabiraki, M. Goto, R. Nakatani, Y. Suzuki and H. Nomura,Applied Physics
Express, 14 (2021).
[5] E. Mengotti, L. J. Heyderman, A. Fraile Rodríguez, A. Bisig, L. Le Guyader, F. Nolting and
H. B. Braun,Physical Review B, 78 (2008).
[6] H. Kubota, S. Tsunegi, K. Yakushiji, T. Taniguchi, S. Tamaru, T. Yamamoto, A. Sugihara,
R. Matsuura, H. Nomura and Y. Suzuki,IEEE Transactions on Magnetics, 59 (2023) 4400704.

Title: The doping-dependent evolution of superconductivity in themultilayered cuprate
J. Jeong1, *, Y. Enomoto2, T. Nakayama2, Y. Kohama1, S. Sakai3, K. Kurokawa1,
S. Shin1, T. Tohyama4, K. Tokiwa2 and T. Kondo1*Presenter
1
Institute for Solid State Physics, the University of Tokyo, Japan
2
Dept. of Applied Electronics, Tokyo University of Science, Japan
3
RIKEN Center for Emergent Matter Science, Japan
4
Dept. of Applied Physics, Tokyo University of Science, JapanThe long debate surrounding the interplay between a superconductivity and an
antiferromagnetic (AF) order in the cuprate high-TC superconductors, has clearly shown thatthe superconducting pair can manifest even in the presence of an AF order, which is evident
from the observation of the pairing gaps in the small Fermi pocket in a multilayered cuprate[1,2]. The small Fermi pocket, which is the indication of a highly underdoped and lowdisordered clean CuO2 plane with long-lived quasiparticles provides plentiful information on
the true nature of the superconductivity in cuprate high-TC superconductors (Fig. 1b, c). To
elucidate the superconductivity with an AF order, it is required to investigate the electronic
structure near the quantum critical points of the AF order. In our study, we focus on the 4layer cuprate Ba2Ca3Cu4O8(F, O)2 (F0234, Fig. 1a), which may have larger carrier densities in
inner CuO2 planes yet clean. Our study employs angle-resolved photoemission spectroscopy(ARPES) to investigate the detailed electronic band structures of the F0234. By studying 4layer samples with different doping levels, we focus on the relationship between the TC andthe superconducting gap sizes, which is related to the essential of the superconductivities ofhighly underdoped cuprate families.
References[1] S. Kunisada et al., Science 369, 6505 (2020).
[2] K. Kurokawa et al., Nat. Commun. 14, 4064 (2023).

Fig. 1 a, The Crystal structure of Ba2Ca3Cu4O8(F, O)2. b, ARPES spectra of F0234 at thenode. c, The energy distribution curves taken along cuts indicated in b. (dashed line)

DFT Calculations on Spin-Splitting Phenomena
in Altermagnetic CaCrO3
Kunihiko Yamauchi* and Thi Phuong Thao Nguyen
Center for Spintronics Research Network, Osaka University, Japan
Altermagnetism has recently emerged as a new class of magnetism, having an alternating spin
configuration and vanishing magnetization in real space [1]. In contrast to conventional
antiferromagnets, altermagnetic materials manifest the spin splitting phenomena in thereciprocal space owing to the magnetic ordering that breaks the PT (parity times time-reversal)
symmetry. This band splitting is guaranteed by the existence of opposite-spin sublattices
connected by the crystal-rotation symmetries. Several collinear antiferromagnetic materials are
identified to exhibit altermagnetism, including RuO2 and MnTe [2].
In this talk, I will review our recent DFT study on CaCrO3 as a prototypical perovskite
transition-metal oxide that exhibits the altermagnetism and the sizable anomalous Hall effect[3]. Our symmetry analysis clarified that the antiferromagnetic order parameter belongs to thesame irreducible representation as the ferromagnetic order parameter in the nonsymmorphic
space group, allowing the nonvanishing Berry curvatures in the reciprocal space. By performing
DFT calculations, we found that the Berry-curvature “hot spots” lie along the gapped nodal
lines where spin-orbit coupling induces the spin splitting of Cr-3d bands near the Fermi energy
and enhances the anomalous Hall effect in CaCrO3.
References[1] L. Šmejkal, J. Sinova, and T. Jungwirth, Phys. Rev. X 12, 031042 (2022);
L. Šmejkal, J. Sinova, and T. Jungwirth, Phys. Rev. X 12, 040501 (2022).
[2] T. Osumi, S. Souma, T. Aoyama, K. Yamauchi, A. Honma, K. Nakayama, T. Takahashi,
K. Ohgushi, and T. Sato, arXiv:2308.10117.
[3] T. P. T. Nguyen and K. Yamauchi, Phys. Rev. B 107, 155126 (2023).

Title: Robust two-qubit entangling gate scheme for collision-freescalable quantum processor
Shinichi Inoue1*, Shotaro Shirai2, Shu Watanabe1, Kohei Matsuura1, Rui Li3,
Shuhei Tamate3, Atsushi Noguchi2,3,4,, and Yasunobu Nakamura1, 3*Presenter
1
Department of Applied Physics, Graduate School of Engineering, The University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2
Komaba Institute for Science (KIS), The University of Tokyo, Meguro-ku, Tokyo, 153-8902,
Japan
3
RIKEN Center for Quantum Computing (RQC), Wako, Saitama 351–0198, Japan
4
Inamori Research Institute for Science (InaRIS), Kyoto-shi, Kyoto 600-8411, Japan
Abstract (up to 200 words)
Quantum computers are gaining more and more attention thanks to their potential applications
to various fields such as biology, finance, and cryptography. Among various implementationsof quantum computers, fixed-frequency transmon qubits are the most studied architecture in thesense of scalability. However, in the contemporary mainstream two-qubit (cross-resonance)gate scheme, it is imperative for the qubit parameters to fall within the "straddling regime." This
imposes heavy constraints on qubit parameter design flexibility, making cross-resonance gatesusceptible to qubit parameter fluctuations.
Recently, a novel two-qubit gate scheme, the coupler-assisted swap (CAS) gate, was proposed.
It was numerically shown that the gate scheme can efficiently perform two-qubit gate outsideof the straddling regime [1]. We have analyzed the newly proposed gate in detail and calculated
the yield rate of collision-free quantum processors using our scheme.
In this presentation, we will introduce the experimental progress in the proposed two-qubit gate
(CAS gate) working outside the straddling regime and numerically compare the yield rate ofquantum processors of our scheme with traditional scheme (CR gate), highlighting that ourscheme enables high-fidelity gate under qubit frequency fluctuations.

References[1] Shotaro Shirai, Yuta Okubo, Kohei Matsuura, Alto Osada, Yasunobu Nakamura, andAtsushi Noguchi. All-Microwave Manipulation of Superconducting Qubits with a FixedFrequency Transmon Coupler. Phys. Rev. Lett. 130, 260601 (2023).

Calculation of the Green function and ionization energy based on
the transcorrelated method
Takumi Chida1*, Shinji Tsuneyuki1
1

Department of Physics, The University of Tokyo, Japan.

Abstract
The transcorrelated (TC) method [1] is a many-body wave function theory that considers theelectron correlation effect through the explicitly correlated wave function using Jastrow factor.
A characteristic feature of this method is a one-body calculation using the non-Hermitianeffective Hamiltonian, which includes up to 3-body interaction terms. In previous studies, theTC method succeeded in calculating some important physical quantities [2-4]. In thispresentation, I will introduce some theoretical progress of this method. In the TC method, theeffective Hamiltonian isn't Hermitian. Hence, the variational principle cannot be applied. In
the first topic, let me explain how to introduce the fundamental equations in this method. The
second topic is defining the Green function for the TC method and computing its self-energy
using perturbation theory. The reconsideration of the Green functions is necessary due to thenon-Hermiticity of the effective Hamiltonian, similar to the introduction of equations. Finally,
we apply it to the 1D half-filling Hubbard model [5] and check the results from the ionizationenergy calculation point of view.

References[1] S. F. Boys and N. C. Handy, Proc. Roy. Soc. A 309, 209 (1969)[2] R. Sakuma and S. Tsuneyuki, J. Phys. Soc. Jpn. 75, 103705 (2006)[3] M. Ochi and S. Tsuneyuki, J. Chem. Theory Comput. 10, 4098−4103 (2014)[4] M. Ochi, R. Arita and S. Tsuneyuki, Phys. Rev. Lett. 118, 026402 (2017)[5] S. Tsuneyuki, Prog. of Theo. Physics Suppl. 176 (2008)

Large Photoelasticity in Topological Antiferromagnet Mn3Sn
Studied by Coherent Acoustic Phonon
Yuchen Wang1*, Takuya Matsuda1,2, Yuta Murotani1, Hanyi Peng2, Takumi
Matsuo2, Tomoya Higo2, Satoru Nakatsuji1,2,3,4, and Ryusuke Matsunaga1,3*Presenter
1
The Institute for Solid State Physics, The University of Tokyo, Japan.
2
Department of Physics, The University of Tokyo, Japan.
3
Trans-scale Quantum Science Institute, The University of Tokyo, Japan.
4
Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins
University, USA.
Abstract
Ultrafast control of magnetism in Weyl antiferromagnet (AFM) Mn3Sn attracts great attention
for its prospect of realizing ultrafast information processing in AFM-based spintronics [1]. In
particular, the responses of the thin film to external perturbation as fast as 1 ps need to beclarified [2]. In this work, we present pump-probe spectroscopy for transient near-infraredtransmission of Mn3Sn thin films and analyze large coherent oscillation induced by the pumppulse.
We used Mn3Sn thin films with thicknesses of 15-50
nm on SiO2 substrate and detected the differential
transmission change with pump and probe pulses at1030 nm with 160-fs duration. A large triangleshaped oscillation of the transmission was observed
after photoexcitation, and the oscillation frequency isinversely proportional to the film thickness. Our
calculation considering pulse-induced coherent
acoustic phonon successfully reproduced the result
and revealed an large photoelastic coefficient of
Mn3Sn in the near-infrared region. We also discuss
the potential to manipulate magnetism bycontrollable acoustic-phonon-related strain field [3]and near-infrared optical response.
References[1] H. Tsai, T. Higo et al., Nature 580, 608 (2020).
[2] T. Matsuda et al., Phys. Rev. Lett. 130, 126302(2023).
[3] M. Ikhlas et al., Nature Phys. 18, 1086 (2022).

Fig.1 (a) Transient transmission of 25
nm Mn3Sn film. The oscillation appearson the offset shown by the dashedcurves. (b) Calculation of the coherent
acoustic wave accompanied by thermal
expansion.

Intense photoexcitation exposes 2000-times higher-mobility
carriers in correlated kagome antiferromagnet Mn3Sn
Takuya Matsuda1*, Tomoya Higo1,2, Kenta Kuroda1,3,4, Takashi Koretsune5,
Natsuki Kanda1, Yoshua Hirai2, Hanyi Peng2, Takumi Matsuo2, Cedric Bareille1,
Naotaka Yoshikawa2, Jun Yoshinobu1, Takeshi Kondo1, Ryo Shimano2,6, Satoru
Nakatsuji1,2,7,8, and Ryusuke Matsunaga1,7*Presenter
1
The Institute for Solid State Physics, The University of Tokyo, Japan.
2
Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
3
Graduate School of Advanced Science and Engineering, Hiroshima University, Japan
4
International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2),
Hiroshima University, Japan
5
Department of Physics, Tohoku University, Japan.
6
Cryogenic Research Center, The University of Tokyo, Japan.
7
Trans-scale Quantum Science Institute, The University of Tokyo, Japan.
8Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins
University, USA
Abstract
Strongly-correlated kagome antiferromagnet Mn3Sn exhibits the colossal anomalous Hall
effect owing to its cluster multipole magnetic structure and the topological band structure
hosting Weyl fermions near the Fermi energy. However, the strong correlation effectsignificantly renormalizes the band structure with quite low mobility of ~1 cm2 V-1 s-1, and thecorrelation effect on the nontrivial band topology in this compound requires vigorous
investigation. Photoexcitation of carriers may mitigate the correlation by screening the
Coulomb interaction.
In this work, employing photocarrier injection, we investigate nonequilibrium carriertransport properties via time-resolved terahertz Faraday spectroscopy. Under equilibrium
conditions or moderate photoexcitation, the anomalous Hall response is dominant [1,2]. By
high-density photoexcitation beyond 1 mJ cm-2, however, a cyclotron resonance is clearlyobserved, indicating the emergence of unusual carriers with higher mobility of ~2600 cm2 V-1
s-1 than that in equilibrium The result can be attributed to a drastic change in the band
structure resulting from the screening of the electron correlation, highlighting the significant
role of many-body effects in this kagome compound in equilibrium [3]. Our work alsosuggests that the electromagnetic response of Weyl fermions may be prominent in thecorrelated kagome magnet Mn3Sn under the extreme nonequilibrium condition.

References[1] T. Matsuda et al., Nat. Commun. 11, 909 (2020).
[2] T. Matsuda et al., Phys. Rev. Lett. 130, 126302 (2023).
[3] T. Matsuda et al., arXiv:2311.12339.

Systematic construction of unconventional η-pairing states in
multi-body interacting systems
S. Imai1* and N. Tsuji1,2*Presenter
1
Department of Physics, University of Tokyo, Japan
2
RIKEN CEMS, Japan
Abstract
The dynamics of quantum many-body systems exhibit various exotic phenomena such as
photoinduced phase transition, quantum time crystal, and quantum computation. In general
Hamiltonian systems, every energy eigenstate behaves similarly to thermal states, but quantum
many-body scar (QMBS) states show nonthermal behavior in a long time even in suchnonintegrable systems, and are important exceptions to thermalization dynamics. We consider
superconducting scar states as promising candidates for nonequilibrium superconductivity,
aiming at superconductivity that can exist even in nonequilibrium states. The η-pairing state
has been studied in the context of superconducting scar states in Refs. [1–3]. Here, we presenta systematic model construction method in which unconventional η-pairing states appear as
QMBSs using multi-body interactions, specifically doublon–electron three-body interactions asshown in Figure. Our strategy is to cancel the energy increase of the colliding Cooper pairs by
the multi-body interactions. We numerically confirm the nonintegrability of the multi-bodyinteracting model and nonthermal properties of the d-wave η-pairing state to prove that theunconventional η-pairing state can be regarded as a QMBS.
References[1] K. Tamura and H. Katsura, Phys. Rev. B 106, 144306 (2022).
[2] L. Gotta et. al, Phys. Rev. B 106, 235147 (2022).
[3] D. Mark et. al, Phys. Rev. B 102, 075132 (2020).

Figure: Schematic picture of
doublon–electron three-bodyinteraction

Energy-Efficient SOT-MRAMs Using Spin Hall Effect ofAmorphous W-Ta-B Alloys
Y. Hibino*, T. Yamamoto, T. Taniguchi, K. Yakushiji, H. Kubota, and S. Yuasa*Presenter
1
National Institute of Advanced Industrial Science and Technology, Research Center for
Emerging Computing Technologies, Japan
Abstract
Spin current generation via spin Hall effect is a key technology to realize fast and reliable writing
operations for spin-orbit-torque magnetoresistive random-access memories (SOT-MRAMs). For
practical application, spin Hall material needs to satisfy several important requirements. Those are highspin Hall angle for energy-efficient writing, high thermal annealing stability for the semiconductor
integration process, and compatibility with CoFeB/MgO-based magnetic tunnel junctions (MTJs). -W
is one of the promising candidate materials because of its large spin Hall angle [1], compatibility withmagnetic tunnel junctions (MTJs) [2,3], and suitability for mass production. Meanwhile, its low thermal
annealing stability has made it a major challenge [4]. Here, we present amorphous W-Ta-B alloys (Fig.
a) as a new candidate spin Hall material [5]. Even without a long-range crystal order, W-Ta-B alloys
exhibit both large effective spin Hall angles up to 40% and superior annealing stability (up to 400C)
enabling them to satisfy the above requirements. We also fabricated nanoscale three-terminal SOTMRAM cells and demonstrated high magnetoresistance ratios up to 130% and low intrinsic switchingcurrent densities down to 4×106 A/cm2 (Fig. b). These results show that amorphous spin Hall materials
can provide the key essence to realizing high-performance SOT-MRAMs.

References[1] C. F. Pai et.al, Appl. Phys. Lett. 101, 122404 (2012).
[2] H. Honjo et.al, IEEE Int. Electron. Devices Meet. (2019), pp. 28.5.1-28.5.4[3] K. Garello et.al, IEEE Int. Memory Workshop (IMW) (2019), pp.101-1104.
[4] K. Kumar et.al, Phys. Rev. Appl. 16, 064009 (2021).
[5] Y. Hibino et.al, Adv. Elec. Mater. DOI: 10.1002/aelm.202300581

Observation of the exchange bias at polycrystalline chiralantiferromagnet/collinear-antiferromagnet interface
M. Asakura1*, T. Higo1, 2, 3, T. Matsuo1, 4, R. Uesugi2, D. Nishio-Hamane2, and
S. Nakatsuji1, 2, 3, 4, 5
1

Department of Physics, The University of Tokyo, Japan
Institute for Solid State Physics, The University of Tokyo, Japan
3
CREST, Japan Science and Technology Agency, Japan
4
Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins
University, USA
5
Trans-scale Quantum Science Institute, The University of Tokyo, Japan
2

Replacing ferromagnets (FMs) in spintronics devices by antiferromagnets (AFMs) has attracted
attention because of the expectation for realizing ultrafast and ultralow power devices [1,2]Recent intensive studies on AFMs with macroscopically broken time reversal symmetry has
solved the difficulty controlling and detecting the antiferromagnetic order with a vanishingly
small magnetization [2,3]. A chiral AFM Mn3Sn is the most studied antiferromagnetic material
possessing such a lower symmetry. The practical integration of AFMs into device architectures
is becoming realistic after the recent experimental confirmation of the electrical control of theantiferromagnetic order via spin orbit torque [4] and its detection through the tunnelingmagnetoresistance in this material [5]. Given the development of ferromagnetic spintronics, thelocal manipulation of the magnetic properties by interlayer coupling such as the exchange bias
effect is essential for developing antiferromagnetic spintronics. For better compatibility withexisting Si-based devices, this manipulation of antiferromagnetic order should be realized inpolycrystalline thin films. In this presentation, we report the exchange bias effect observed at
the interface between polycrystalline Mn3Sn and collinear AFM MnN films on an amorphous
substrate.
References[1] T. Jungwirth, et. al., Nat. Nanotechnol. 11, 231 (2016).
[2] S. Nakatsuji and R. Arita, Annu. Rev. Condens. Matter Phys. 13, 119 (2022).
[3] S. Nakatsuji, N. Kiyohara, T. Higo, et. al., Nature 527, 212 (2015).
[4] H. Tsai, T. Higo, et. al., Nature 508, 608 (2020); T. Higo, K. Kondou, et. al., Nature, 607,
474 (2022).
[5] X. Chen, T. Higo, K. Tanaka, et. al., Nature 613, 490 (2023).

Title: Magneto transport properties of Ferri magnet GdCo2
T.Matsumoto1*, H.Nakamura1, Y.Wang1, H.Su1, S.Minami1,2, D.Hamane3,
A.Sakai1, S.Nakatsuji1*Presenter
1
Dept of Phys, Univ. of Tokyo, Japan
2
Faculty of Engineering, Kyoto Univ., Japan
3
The Institute for Solid State Physics, Japan
Abstract (up to 200 words)
In recent years, magnetic materials exhibiting large anomalous Nernst effects have attracted
much attention in the studies of thermoelectric materials [1]. The anomalous Nernst effect is aphenomenon in which a voltage difference orthogonal to both magnetization and atemperature gradient emerges, and is known to be enhanced by the sum of Berry curvaturenear the Fermi level [2,3]. Many existing thermoelectric devices use the Seebeck effect, butusing the anomalous Nernst effect has advantages such as enabling the creation of thinner
devices and reducing contact resistance[4].
From the viewpoint of application, magnetic materials with a high Curie temperature andlarge thermoelectromotive force Syx are required. In this study, we focused on theferrimagnet GdCo2 as a magnetic material with the highest Curie temperature of 405 K in the
RCo2 (R: rare earth) system[5].
In this talk, I will report on the anomalous Nernst effect and various physical properties
measured for Ferri magnet GdCo2, which is predicted to have a large density of states near
the Fermi level based on first-principles calculations. We also compare our results withpredictions of physical properties based on first-principles calculations.

References[1] Nakatsuji & Arita, Annual Review of Condensed Matter Physics 13, 119-142 (2022)[2] Nagaosa, N., Sinova, J., Onoda, S., MacDonald, A. H. & Ong, N. P. Anomalous Hall efect.
Rev. Mod. Phys. 82, 1539–1592 (2010).
[3] Xiao, D., Chang, M.-C. & Niu, Q. Berry phase effects on electronic properties. Rev. Mod.
Phys. 82, 1959–2007 (2010).
[4] Mizuguchi & Nakatsuji, STAM, 20(1), 262-275(2019).
[5] K.W.Zhou et al., Solid State Communications 137, 275 (2006).

Magneto-Thermoelectric Effect in Epitaxial Thin Film ofTopological Nodal Plane Kagome Ferromagnet Fe3Sn
Shun’ichiro Kurosawa*1, Tomoya Higo1,2, Shota Saito1, Ryota Uesugi2, Satoru
Nakatsuji1,2,3,4,5
1

Department of Physics, Faculty of Science and Graduate School of Science, The Universityof Tokyo, Hongo, bunkyo-ku, Tokyo 113-0033, Japan
2

Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan

3

Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins
University, Baltimore, MD 21218, U.S.A
4

Trans-scale Quantum Science Institute, University of Tokyo, Hongo, bunkyo-ku, Tokyo 1130033, Japan
5

Canadian Institute for Advanced Research, Toronto, M5G 1Z7, ON, Canada

Recent intensive research on various kagome metallic systems has revealed abundant
electronic phases such as the correlated topological states, charge density wave ordering, andsuperconductivity [1-3]. Among them, the Fe–Sn compounds are a well-known platform witha complex interplay of topological band structures, electronic correlations, and magnetism [4].
More recently, large transverse responses have been observed even in nano-structure Fe–Sn
films due to the Berry curvature originating from the short-range ordering of the kagome latticefragments [5].
In the kagome ferromagnet Fe3Sn, both theoretical and experimental studies have shown theexistence of a novel topological band structure, nodal plane, near the Fermi level, leading to thelarge transverse thermoelectric conductivity αyx and anomalous Nernst effect (ANE) at room
temperature [6], which is suitable for thermoelectric device applications [7]. Although thinfilms are essential to realize thermoelectric devices using ANE, the thermoelectric propertiesof Fe3Sn films have not been clarified. Here, we have fabricated (0001)-oriented epitaxial thinfilms of Fe3Sn and investigated their magnetic and magneto-transport properties. In thispresentation, we will discuss the thermoelectric properties of our film based on αyx, sensitive tothe band structure near the Fermi energy.
References[1] S. Nakatsuji, N. Kiyohara, and T. Higo, Nature 527, 212 (2015).
[2] B. R. Ortiz et al., Phys. Rev. Mater. 3, 094407 (2019)[3] J. X. Yin et al., Nature 583, 533–536 (2020).
[4] L. Ye et al., Nature 555, 638–642 (2018); M. Kang et al., Nat. Mater. 19, 163–169 (2020).
[5] K. Fujiwara et al., Nat. Commun 14, 3399 (2023).
[6] T. Chen et al., Sci. Adv. 8, eabk1480 (2022).
[7] Y. Sakuraba et al., APEX 6, 033003 (2013).

Observation of orbital Hall effect in Ru/FM nanostructures
D. Catala1*, H. Isshiki1, and Y. Otani1,2,3*Presenter
1
Institute for Solid State Physics, The University of Tokyo, Japan
2
Trans-scale Quantum Science Institute, The University of Tokyo, Japan.
3
Center for Emergent Matter Science, RIKEN, Japan
Recently, the Orbital Hall Effect (OHE) has been intensively explored as an alternative to thespin Hall effect (SHE). The OHE generates a transverse orbital current via the application of acharge current, represented by 〈𝑳〉 = 𝒌 × 𝑱 where 𝑱 is the charge current density [1]. This study
aims to explore the OHE and orbital currents by electrically detecting orbital accumulation(OA) in Ruthenium nanowires; Ru is a suitable platform to study OHE due to its small spinorbit coupling and its 5d unfilled shell. Additionally, theoretical predictions indicate a large
orbital hall conductivity [2-4].
We employed lateral devices consisting of an OH material wire connected to two
ferromagnetic wires (FM) that detect spin accumulation converted from the OA via spin-orbit
interaction (Fig.1.a). A current flowing in the Ru wire generates the OA that diffuses into FM
wires where two FM detectors can measure an electrochemical potential difference. This study
provides evidence for OHE in Ru/FM transport nanostructure (Fig.1.b), Ru thickness
dependence, and temperature dependence of OA signal. These experiments offer an alternative
approach to studying OHE, allowing us to clarify orbital transport properties in ruthenium andother materials. This understanding holds significance for potential applications in future
orbitronics.

Figure 1 a) Schematics of the local orbital accumulation device. H is an external magnetic
field, the different switching fields of these wires allow us to reach the antiparallel
magnetization state and measure a voltage between them. b) Orbital accumulation measurement
signal, the arrows illustrate the magnetization configuration of the FM detectors.
References[1] Kim, J., & Otani, Y. (2022). Journal of Magnetism and Magnetic Materials, 563, 169974.
[2] Liao, L, et al. (2022). Physical Review B, 105(10), 104434.
[3] Kontani, H et al. (2009). PRL, 102(1), 016601.
[4] Salemi, L., & Oppeneer, P. M. (2022). Physical Review Materials, 6(9), 095001.

Title: Pump-probe spectroscopy of NiFe film grown on chiralantiferromagnet Mn3Sn
Hidetoshi Kosaki1*, Shoya Sakamoto1, Tempei Hatajiri1, Tomoya Higo1, 2, 3,Satoru Nakatsuji1, 2, 3, 4, and Shinji Miwa1, 3, 4
*Presenter
1
The Institute for Solid State Physics, The University of Tokyo, Japan2
Department of Physics, The University of Tokyo, Japan
3
CREST, Japan Science and Technology Agency, Japan
4
Trans-scale Quantum Science Institute, The University of Tokyo, Japan
Abstract (up to 200 words)
D019-Mn3Sn is a typical chiral antiferromagnet (Fig 1a). It has attracted attention due to its
magnetic effects, such as the anomalous Hall effect [1]. While most research on spintronics
devices has utilized multilayers of Mn3Sn and ferromagnetic metals [2], the spin dynamics inferromagnetic metals interfaced with Mn3Sn remain unclear. This research investigates thespin dynamics in Mn3Sn/Ni81Fe19 bilayer using time-resolved magneto-optical Kerr effect(TR-MOKE) measurements (Fig. 1b).
A MgO(110) substrate/W (7 nm)/Mn3Sn (20 nm)/MgO (0-3.5 nm)/Ni81Fe19 (4 nm) sample
was fabricated using the molecular beam epitaxy method. The Gilbert damping constant of
NiFe was evaluated from the free induction decay (Fig. 1c), obtained via TR-MOKE. An
enhancement of the Gilbert damping constant was observed when the thickness of the MgO
insertion layer was less than 1 nm. The mixing conductance comparison with that reported in
the previous study [3] will be discussed.
This work was partly supported by JSPS KAKENHI, JST-Mirai Program, Spin-RNJ, and XNICS.
References[1] S. Nakatsuji et al., Nature 527, 212 (2015).
[2] M. Kimata et al., Nature 565, 627 (2019).
[3] H. Bangar et al., Adv. Quantum Technol., 6, 2200115, (2023)

Fig. 1 (a). Spin and crystal structures of Mn3Sn. (b) Schematic of the TR-MOKE experiment. (c)Typical measurement results.

The accuracy of the harmonic Hall measurements on spin orbit
torques in W/CoFeB
Y. Marui1,2*, M. Kawaguchi1, M. Hayashi1,31Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
3
Trans-scale Quantum Science Institute, The University of Tokyo, Tokyo 113-0033, Japan
2

Spintronics is a field that actively utilizes the spin degree of freedom of electrons in addition
to the charge degree of freedom. One of the representative phenomena of spintronics is the spin
Hall effect [1,2]. Harmonic Hall measurement [3–5] is widely used to evaluate the magnitudeof the spin Hall effect because it combines relatively low measurement difficulty with highmeasurement accuracy. On the other hand, when considering perpendicular magnetic films, it
is known that the measurement does not work well for systems with specific conditions, suchas W/CoFeB [6,7]. The objective of this study is to clarify the reason behind this and clarify thelimitation of this technique.
We prepared W (3)/CoFeB (1) perpendicularly magnetized film by RF sputtering andfabricated it into a Hall bar by photolithography. We performed harmonic Hall measurementson the same sample in the in-plane and out-of-plane magnetization configurations. The
estimated spin torque efficiency showed a significant dependence on the ratio 𝑟 of the planar
Hall effect to the anomalous Hall effect, and the magnetic anisotropy field 𝐻k . We evaluatedthe impact of 𝑟 and 𝐻k on the harmonic Hall measurements using model calculations. In thepresentation, we discuss the limitations of harmonic Hall measurements and provide guidelines
for further improving the measurement accuracy.
References[1] M. I. D’yakonov and V. I. Perel, Current-Induced Spin Orientation of Electrons in
Semiconductors, Phys. Lett. A 35, 459 (1971).
[2] J. E. Hirsch, Spin Hall Effect, Phys. Rev. Lett. 83, 1834 (1999).
[3] U. H. Pi, K. Won Kim, J. Y. Bae, S. C. Lee, Y. J. Cho, K. S. Kim, and S. Seo, Tilting of theSpin Orientation Induced by Rashba Effect in Ferromagnetic Metal Layer, Appl. Phys. Lett.
97, 162507 (2010).
[4] M. Hayashi, J. Kim, M. Yamanouchi, and H. Ohno, Quantitative Characterization of theSpin-Orbit Torque Using Harmonic Hall Voltage Measurements, Phys. Rev. B 89, 144425(2014).
[5] C. O. Avci, K. Garello, M. Gabureac, A. Ghosh, A. Fuhrer, S. F. Alvarado, and P.
Gambardella, Interplay of Spin-Orbit Torque and Thermoelectric Effects in
Ferromagnet/Normal-Metal Bilayers, Phys. Rev. B 90, 224427 (2014).
[6] J. Torrejon, J. Kim, J. Sinha, S. Mitani, M. Hayashi, M. Yamanouchi, and H. Ohno,
Interface Control of the Magnetic Chirality in CoFeB/MgO Heterostructures with HeavyMetal Underlayers, Nat. Commun. 5, 4655 (2014).
[7] S. J. Yun, E.-S. Park, K.-J. Lee, and S. H. Lim, Accurate Analysis of Harmonic Hall Voltage
Measurement for Spin–Orbit Torques, NPG Asia Mater. 9, e449 (2017).

First-Principles Electrical Conductivity Calculations of Ag-Pd
Alloy based on Wannier-CPA Method:

Shota Namerikawa*, Takashi Koretsune*Presenter
Department of Physics, Tohoku University, Japan
Abstract
In material design, it is important to predict the properties of mixed crystals bycontinuously changing their compositions. For this purpose, coherent potential
approximation (CPA) is a powerful tool. However, due to its formulation, DFT-based
CPA has been implemented only in specific electronic-structure-calculation packages,
such as those based on the KKR or TB-LMTO methods.
Recently, Wannier-function based CPA (Wannier-CPA) [1] has been developed, whichis computationally efficient and can be easily combined with any DFT packages. It was
confirmed that this method well reproduces magnetic properties of Fe-based transition
metal alloys obtained by KKR-CPA. To apply this method for transport properties, wedevelop a code to calculate the electrical conductivity of substitutional alloys based on
Wannier-CPA. For the analytic continuation of the response function, two numericalanalytic continuation methods are employed [2]. We find that the results well reproduce
previous experimental and theoretical studies [3,4].
References[1] N. Ito et al., Phys. Rev. B 105, 125136 (2022).
[2] K. Nogaki and H. Shinaoka, J. Phys. Soc. Jpn. 92, 035001 (2023).
[3] A. M. Guenhault, Phil. Mag. 30, 641, (1974).
[4] P. R. Tulip et al., Phys. Rev. B 77, 165116 (2008).

Theoretical study on anomalous Nernst effect enhanced at van
Hove singularity in two-dimensional materials
K. Shibata1*, N. Yamaguchi2, H. Sawahata2, F. Ishii2*Presenter
1
Graduate School of Natural Science and Technology, Kanazawa University, Japan
2
NanoMaRi, Kanazawa University, Japan
Abstract
The thermoelectric effect is a phenomenon where a temperature gradient generates an electricfield and can effectively harness waste heat. Two primary types of thermoelectric effects exist
the longitudinal (Seebeck) and the transverse (Nernst). The Seebeck effect generally yields ahigher thermoelectric conductivity than the Nernst effect. On the other hand, the Nernst effectoffers the advantage of simplicity and durability in thermoelectric devices.
Our research involved conducting model calculations on a kagome lattice with a chiral spinstate, specifically focusing on the density of states (DOS) and subsequent thermoelectric
conductivity. Notably, the DOS exhibits singularities known as van Hove singularities (VHS).
Our findings demonstrated that these VHS enhanced thermoelectric conductivities, leading to
the anticipation of a significant anomalous Nernst coefficient, approximately 10 µV/K at 50 K
[1].
To explore a more practical system, we performed first-principles calculations on the twodimensional ferromagnet CrGeTe3, which was observed experimentally [2]. This calculation
resulted in identifying a nodal line and the computation of the DOS associated with this nodal
line. It was reported that VHS of the nodal line DOS enhanced thermoelectric conductivity [3].
In our study on CrGeTe3, a large thermoelectric conductivity was obtained at the VHS of thenodal line DOS.
References[1] Kaiki Shibata, Naoya Yamaguchi, Hikaru Sawahata, and Fumiyuki Ishii, Thermoelectric
Effect in Kagome Lattice Enhanced at Van Hove Singularities, J. Phys. Soc. Jpn. 92, 124704(2023).
[2] Cheng Gong, Lin Li, Zhenglu Li, Huiwen Ji, Alex Stern, Yang Xia, Ting Cao, Wei Bao,
Chenzhe Wang, Yuan Wang, Z. Q. Qiu, R. J. Cava, Steven G. Louie, Jing Xia, and Xiang
Zhang, Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals,
Nature 546, 265 (2017).
[3] Susumu Minami, Fumiyuki Ishii, Motoaki Hirayama, Takuya Nomoto, Takashi Koretsune,
and Ryotaro Arita, Enhancement of the transverse thermoelectric conductivity originatingfrom stationary points in nodal lines, Phys. Rev. B 102, 205128 (2020).

Topological degeneracy and emergence of transport phenomena
in antiferromagnetics
Vu Thi Ngoc Huyen1*, Michi- To Suzuki1
1 Institute for Materials Research, Tohoku University, JapanThe transport phenomena in antiferromagnetic (AFM) nowadays has much attention
because of its advantages in spintronic applications such as faster spin dynamic or higher energy
efficiency than in ferromagnet. The effects were well characterized through the topologicalaspect via Berry phase concept. Recently, it has been experimentally observed some certain
AFMs belongs to the same space group Pnma class. They have magnetic moments of 3delectrons on Mn atoms order in a collinear-AFM CuMnAs [1] or a zigzag-AFM NbMnP [2] atroom temperature. The CuMnAs has been noted for the emergence of the spin Hall effect from
Dirac nodal lines in the ky=0 plane [3]. On the other hand, the NbMnP also exhibits significant
Berry curvature around Fermi surfaces in the plane and has a large anomalous Hall conductivity[2]. This work aims to analyze the detailed topology degeneracy of the AFM states in CuMnAs
and NbMnP, with and without SOC, to understand the origin of their significant transportphenomena.
References[1] F. Máca, et al. 324, 1606–1612 (2012).
[2] H. Kotegawa, Y. Kuwata, V. T. N. Huyen, Y. Arai, H. Tou, M. Matsuda, K. Takeda, H.
Sugawara and M.-T. Suzuki, npj Quantum Materials 8, 56 (2023).
[3] V. T. N. Huyen, Y. Yanagi, and M.-T. Suzuki, Phys. Rev. B 104, 035110 (2021).

Dynamic Redox Reaction-Driven Electrically Tunable Magnon
FET
Md Shamim Sarker1,*, Hiroyasu Yamahara1, Kenyu Terao2, Siyi Tang2, EMK
Ikbal Ahamed2, Munetoshi Seki2 and Hitoshi Tabata1,2
1Department of Bioengineering, The University of Tokyo, Japan
Department of Electrical Engineering and Information Systems, The University of Tokyo,Japan
2Spin-waves offer Joule heating-less data transmission capability and additional degree of
freedoms like phase, frequency, wavelength etc. However, energy efficient control of magnon
is still missing. Here, we propose a new dynamic redox reaction-based approach in an
Au/PEDOT:PSS/Pt/YIG heterostructure (Fig.1(a)). Here, the SWs propagate along the surface
of YIG while the switching voltage is applied across PEDOT:PSS. The propagation of Spinwaves (Fig.1(b)) for different voltage levels. Under electric field −OH from PSS dissociate toyield H+ ions, which selectively target the double bond in the PEDOT chain (Fig.1(c)), resulting
in the formation of C+ (at PEDOT) and O− (at PSS) ions [1]. By manipulating the potential at
the Pt terminal (Fig.1(d) and (e)), C+ and O− ions can be preferentially directed. Specifically, inFig. 1(d), Pt acquires electrons from O−, leading to an excess of electrons in Pt. The d-orbital
filling reduces the spin-orbit interaction in the Pt layer, resulting in lower spin relaxation [2],reduced damping, and increased magnetization in the Pt/YIG bilayer. Conversely, applying an
opposite polarity initiates a reverse chain of effects. The occurrence of the redox reaction isevidenced by the cyclic voltammetry measurement displayed in Fig.1(f).

Acknowledgement
This research was partially supported by Institute for AI and Beyond for the University ofTokyo and JST-CREST Grant Number JPMJCR22O2, Japan.
References[1] N. Aishah et al., Mater. Adv., 2, 7118-7138 (2021)[2] S. Dushenko et al., Nat. Comm 9, 3118 (2018)

Anti-Poiseuille flow by spin Hall effectJ. Fujimoto1,*, W. Koshibae2, and S. Maekawa2,3,4*Presenter
1
Saitama University, Japan
2
RIKEN CEMS, Japan
3
KITS, UCAS, China
4
JAEA ASRC, Japan
Hydrodynamics emerges in electric current when the electron-electron interaction dominates
over the other momentum-nonconserving scatterings. The hydrodynamic equation that
describes the electric current includes viscosity, extending beyond the Ohmic transport[1]. In
this paper, we show an exotic class of viscous electron fluid, arising in electron systems
exhibiting the spin Hall effect (spin Hall systems), where the orbital and spin motions arecoupled. Such a viscous electron fluid emerges even in non-interacting electron systems, andthe current density exhibits a minimum in the center of a flow and a maximum at the edges,
i.e., an anti-Poiseuille flow[2] realizing. We also find that the spin accumulation by the spin
Hall effect is connected to the electric current vorticity in two-dimensional spin Hall systems.
We propose a novel guiding principle to manipulate topological magnetic textures from thehydrodynamic viewpoint. By solving the hydrodynamic equation in a two-dimensional spin
Hall system with a cavity and employing micromagnetic simulations for an attached chiralmagnetic insulator, we demonstrate that spin accumulation near the cavity's boundary leads tothe creation of a magnetic skyrmion. Our research illuminates new aspects of electronhydrodynamics and spintronics, contributing significant insights to the fields.

References[1] M. Polini and A. K. Geim, Viscous Electron Fluids, Physics Today 73, 28 (2020).
[2] B. N. Narozhny, I. V. Gornyi, and M. Titov, Anti-Poiseuille Flow in Neutral Graphene,
Phys. Rev. B 104, 075443 (2021).

Surface and bulk magnetic structure of Mn3Sn epitaxial thin films
studied by x-ray magnetic circular dichroism
S. Sakamoto1*, T. Higo2,1,3, Y. Kotani4, H. Kosaki1, M. Shiga1, D. NishioHamane1, T. Nakamura4,5, S. Nakatsuji2,1,3,6,7, and S. Miwa1,6,5*Presenter
1
The Institute for Solid State Physics, The University of Tokyo, Japan2
Department of Physics, The University of Tokyo, Japan
3
CREST, Japan Science and Technology Agency (JST), Japan
4
Japan Synchrotron Radiation Research Institute (JASRI), Japan
5
International Center for Synchrotron Radiation Innovation Smart, Tohoku University, Japan
6
Trans-scale Quantum Science Institute, The University of Tokyo, Japan
7
Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins
University, USA
Abstract (up to 200 words)
The chiral antiferromagnet Mn3Sn has attracted considerable attention due to its robust
ferromagnetic responses, despite the absence of net magnetization [1]. Recent development of
Mn3Sn epitaxial thin films has led to the demonstration of full electrical switching of
antiferromagnetic order [2]. For further advancement in this field, it is necessary to clarify
whether chiral antiferromagnetic order is consistently realized across the entire film,
encompassing surface and bulk regions.
In this study, we fabricated an epitaxial Mn3Sn thin film consisting of MgO (110)substrate/W (7 nm)/Mn3Sn (30 nm)/MgO (3 nm) using the molecular beam epitaxy method.
We performed x-ray magnetic circular dichroism (XMCD) measurements on using both total
electron-yield (TEY) and partial fluorescence-yield (PFY) modes, with probing depths
typically of 5 nm and 100 nm, respectively. This difference in probing depth can clarify
whether there are variations in magnetic and electronic structures between the surface andbulk regions. The XMCD experiments were performed at the beamline BL25SU of SPring-8.
The obtained TEY XMCD spectra were consistent with those reported in a previous study [3].
Notably, PFY XMCD spectra closely resemble TEY spectra, indicating the realization of noncollinear chiral antiferromagnetic order throughout the Mn3Sn layer.
This work was partly supported by JSPS KAKENHI, JST-Mirai Program, Spin-RNJ, and XNICS.
References[1] S. Nakatsuji et al., Nature 527, 212-215 (2015)[2] T. Higo et al., Nature 607, 474–479 (2022)[3] S. Sakamoto et al., Phys. Rev. B 104, 134431 (2021)

Title: Electrical control of skyrmionic lattice in centrosymmetricnon-frustrated insulating magnets
R. Ono1**Presenter
1
National Institute for Materials Science, Japan
Abstract
The integration of electric control over magnetism via the magnetoelectric effect presents
significant potential for the advancement of multiferroic materials in the development of
future technological devices [1]. A particularly interesting magnetic configuration is theskyrmionic lattice, which stands out both for its fundamental significance and its application
potential. Commonly, the stabilization of skyrmions involves Dzyaloshinskii-Moriya (DM)interactions or magnetic frustrations with anisotropy. Especially, in centrosymmetric magnets,
the emergence of a skyrmionic phase is predominantly observed in systems characterized bymagnetic frustration with anisotropy [2].
In this talk, we explore a new mechanism: the stabilization of skyrmions in non-frustrated
centrosymmetric magnets through external stimuli. Our approach utilizes a Ginzburg-Landau
type theoretical framework to provide a comprehensive analysis of this phenomenon. A
prediction of our model extends beyond the skyrmionic phase, highlighting the capacity ofminimal electric fields to induce transition of spiral magnetic structures, such as transition
between cycloidal and proper-screw type spirals. As an illustrative example, we explore
several quasi-2D centrosymmetric magnetic insulator, discussing its potential as a candidate
material for demonstrating the discussed effects. This work not only advances ourunderstanding of skyrmionic stabilization mechanisms but also opens avenues for electricallycontrolled magnetic structures in practical applications.
References[1] J. White, et. al., J. Phys: Consens. Matter 24 432201 (2012).
[2] J. A. M. Paddison, et. al., Phys. Rev. Lett. 129 137202 (2022).

Title: Supercurrent Distribution on Superconducting Quasicrystals
T. Fukushima1*, N. Takemori2, S. Sakai3, M. Ichioka4, and A. Jagannathan5*Presenter
1
Institute for Solid State Physics, The University of Tokyo, Japan
2
Center for Quantum Information and Quantum Biology, Osaka University, Japan
3
Center for Emergent Matter Science, RIKEN, Japan
4
Research Institute for Interdisciplinary Science, Okayama University, Japan
5
Laboratoire de Physique des Solides, Univerité Paris-Saclay, France
Abstract (up to 200 words)
Quasicrystal is a solid that shows sharp Bragg peaks although it does not have periodicity
in its structure [1,2]. Therefore, it often exhibits unique electronic states. Recently, the first bulk
superconductivity was reported in Al-Mg-Zn quasicrystal [3] while it breaks the prerequisite of
the Bardeen-Cooper-Schrieffer (BCS) theory such as the well-defined momentum space. On
the other hand, some theoretical works pointed out some exotic superconducting states,
particularly the existence of Cooper pairs with finite center-of-mass momentum in the weakcoupling region even without an external magnetic field [4,5].
Motivated by such works, we studied the spatial distributions of the local supercurrent
induced by a uniform vector potential [6,7]. The attractive Hubbard model was numericallystudied within the Bogoliubov-de Gennes mean field theory. We will show that non-uniform
supercurrent distributions can be realized under inhomogeneous superconducting states inquasicrystals. Furthermore, it is clarified that the paramagnetic components of the supercurrents
can flow in a direction perpendicular to the applied vector potential and are finite even at zerotemperature. Such phenomena can also be expected in the Fulde-Ferrell-Larkin-Ovchinnikov(FFLO) state [8,9], however, we note that our results make experimental access much easier
because a proper adjustment of the magnetic field is unnecessary in quasicrystals.

References[1] D. Shechtman et al., Phys. Rev. Lett. 53, 1951 (1984).
[2] D. Levine et al., Phys. Rev. Lett. 53, 2477 (1984).
[3] K. Kamiya et al., Nat. Commun. 9, 154 (2018).
[4] S. Sakai et al., Phys. Rev. B 95, 024509 (2017).
[5] N. Takemori et al., Phys. Rev. B 102, 115108 (2020).
[6] T. Fukushima et al., J. Phys.: Conf. Ser. 2461, 012014 (2023).
[7] T. Fukushima et al., Phys. Rev. Res. 5, 043164 (2023).
[8] P. Fulde and R. A. Ferrell, Phys. Rev. 135, A550 (1964).
[9] A. I. Larkin and Y. N. Ovchinnikov, Sov. Phys. JETP 20, 762 (1965).

Title: Shift current responses of a two-dimensional systemapproaching the Weyl semimetal phase
H. Yoshida1*, T. Zhang1,2, and S. Murakami1*Presenter
1
Tokyo Institute of Technology, Japan
2
Chinese Academy of Science, China
Abstract (up to 200 words)
In our recent studies, we revealed that the electric polarization of a two-dimensional system
has a finite jump when the system changes across a two-dimensional Weyl semimetal phase.
We derived a concise formula to describe this jump of polarization using a newly introduced
quantity “Weyl dipole” [1,2]. This jump can be understood to have originated from the U(1)gauge redundancy of quantum states and the multivaluedness of the electric polarization.
Motivated by these results, we investigate the shift current responses of twodimensional systems in a limit where the system approaches the two-dimensional Weyl
semimetal phase. The shift current is a kind of nonlinear optical response and intimately
related with the electric polarization [3]. Thus, we can expect a singular behavior of the shift
current when the system approaches a two-dimensional Weyl semimetal phase. We
numerically and analytically find that the shift current conductivity behaves inversely
proportional to the light frequency and diverges in a two-dimensional Weyl semimetal limit.

References[1] H. Yoshida, T. Zhang, and S. Murakami, Phys. Rev. B 107, 035122 (2023).
[2] H. Yoshida, T. Zhang, and S. Murakami, Phys. Rev. B 108, 075160 (2023).
[3] B. M. Fregoso, T. Morimoto, and J. E. Moore, Phys. Rev. B 96, 075421 (2017)

Title: Current-induced orbital polarization at Cu/Oxide interface
Junyeon Kim1*, and YoshiChika Otani1, 2*Presenter
1
RIKEN-CEMS, Japan
2
ISSP, the University of Tokyo, Japan
Abstract (up to 200 words)
Current-induced orbital polarization and orbital transport open an alternative spin manipulation
mechanism [1,2]. The current-induced orbital polarization could introduce a novel functionality
to Spintronic devices, particularly due to its broad material range, which is attributed to its
independence from spin-orbit coupling (SOC).
In this study, we focused on current-induced orbital polarization at Cu/Oxide interfaces [3].
The selected oxides were MgO, Al2O3, SiO2, and TiO2, with cations having similar atomic
numbers to avoid unintended impacts from the SOC. The efficiency of the current-induced
orbital polarization was measured using torque efficiency in ferromagnet/Cu/Oxide films. As aresult, we found that the Cu/SiO2 interface is the most efficient system in terms of orbital
polarization. The efficiency decreases in order of the Cu/TiO2, Cu/MgO, and Cu/Al2O3
interfaces. Based on the torque efficiency results and material characterizations, we conclude
that promoting the interaction between p-orbital of oxygen atoms and d-orbital of Cu atoms isa key factor in advancing orbital polarization in these material systems. Further discussion will
be provided during the conference.
References[1] J. Kim et al., Phys. Rev. B 103, L020407 (2021).
[2] J. Kim et al., J. Magn. Magn. Mater. 563, 169974 (2022).
[3] J. Kim et al., Phys. Rev. Mat. 7, L111401 (2023).

Title: Wannier-Stark ladders emerging in the single-particle
excitation spectra of the Hubbard model
K. Sugimoto1**Presenter
1
Department of Physics, Keio University, Japan
Abstract (up to 200 words)
Phenomena induced by dc electric fields in strongly correlated electron systems, such as
Mott breakdown and field-induced magnetism, have been widely discussed bothexperimentally and theoretically. Recently, intense terahertz light pulses generated fromsynchrotron radiation have attracted particular attention as a method for observing these
phenomena [1] since the energy of terahertz light is quite small compared to the characteristicenergy of Mott insulators and it can be regarded as a low-frequency limit, i.e., almost a dc
electric field. By using this terahertz light as the pump light and examining the dynamical
response from the probe light, the properties of strongly correlated materials in a dc electricfield can be clarified [2].
In this study, we investigate single-particle excitation spectra of the one-dimensional
Hubbard model under a dc electric field, employing an infinite matrix-product-state
representation. In the Hubbard model, the lower and upper Hubbard bands appear in the
excitation spectra due to the opening of the Mott gap, and the spectra split into multiple peaksby the field. This result can be understood as the appearance of a Wannier-Stark ladder [3]due to a tilted potential.
References[1] D. Nicoletti and A. Cavalleri, Adv. Opt. Photonics 8, 401 (2016).
[2] M. Udono, T. Kaneko, and K. Sugimoto, Phys. Rev. B 108, L081304 (2023).
[3] Y. Murakami and P. Werner, Phys. Rev. B 98, 075102 (2018).

Microscopic Mechanism of Magnetic Stability
in Monolayer Transition-Metal Dihalides
Thi Phuong Thao Nguyen* and Kunihiko Yamauchi
Center for Spintronics Research Network, Osaka University, Japan
Boosted by the experimental discovery of intrinsic ferromagnetism (FM) in atomically thinlayers of CrI3 and Cr2Ge2Te6, two-dimensional (2D) magnets have recently received increasing
attention [1,2]. On the other hand, 2D antiferromagnetic (AFM) materials, such as NiPS3 and
MnPS3, have been reported very recently as candidate materials appealing for antiferromagnetic
spintronics applications [3]. Typically, 2D triangular lattice causes magnetic frustration andoften results in non-collinear magnetic orderings such as 120° AFM configuration. In this study,
we performed first-principles calculations to investigate the magnetism in a series of monolayer
MCl2 (M=V, Mn, and Ni) [4, 5]. These materials are composed of light elements, and then we
can ignore the spin-orbit-coupling effect and focus on the Heisenberg interactions. The resulting
magnetic stability manifests a distinct chemical trend; VCl2 and MnCl2 show the 120° AFM
ground states, and NiCl2 shows the FM ground state. To understand the microscopic mechanism
behind the magnetic interaction, we extracted the exchange coupling constants and the hopping
integrals via the Wannier-function scheme. We also referred to Goodenough-KanamoriAnderson rules to explain the trend of magnetic interaction. Our result highlights the role of theparticular orbital states responsible both for the direct and superexchange interaction in 2D
magnetism.
References[1] T. P. T. Nguyen, K. Yamauchi, T. Oguchi, D. Amoroso, and S. Picozzi, Phys. Rev. B 104,
014414 (2021).
[2] A. De Vita, T. P. T. Nguyen, ..., K. Yamauchi, S. Picozzi, and G. Panaccione, Nano Lett. 22,7034 (2022).
[3] K. Kim, S. Y. Lim, J.-U. Lee, S. Lee, T. Y. Kim, K. Park, G. S. Jeon, C.-H. Park, J.-G. Park,and H. Cheong, Nat. Commun. 10, 345 (2019).
[4] K. Riedl, D. Amoroso, S. Backes, A. Razpopov, T. P. T. Nguyen, K. Yamauchi, P. Barone,
S. M. Winter, S. Picozzi, and R. Valentí, Phys. Rev. B 106, 035156 (2022).
[5] T. P. T. Nguyen, and K. Yamauchi, arXiv:2308.06068.

Long spin diffusion length in epitaxial Pt wires.
Keisuke Sobue1*, Zheng Zhu1, Hironari Isshiki1, and Yoshichika Otani1, 2
1

Institute of Solid Physics, University of Tokyo, Japan
2
RIKEN-ASI, Japan
Polycrystalline platinum is a commonly used spin Hall (SH) material with a good SH
angle but a small spin diffusion length due to the strong spin-orbit coupling.[1]. We
recently found that an epitaxially grown Pt exhibits a long spin diffusion length of about
100 nm.[2]. In this study, we measured the non-local SH effect using epitaxial andpolycrystalline Pt H-shaped devices [3] to determine their spin diffusion lengths and SH
angles.
Figure (a) shows fabricated H-shaped epitaxial and polycrystalline platinum
nanostructures. An applied current along the left arm generates a diffusive spin current
in the horizontal bar via the SHE. The spin current then diffuses into the right arm andis converted back to the charge current via the inverse SHE. The voltage is detected asa non-local voltage. The non-local resistance comprises three contributions including
the SHE contribution. Using the optimized structure, we extracted the SHE contribution
from the systematic temperature dependence measurements.
The polycrystalline and epitaxial Pt device results are shown in Figs. (b) and (c),respectively. Interestingly, the (𝑅𝑛𝑙 /𝑅0 )𝑝𝑜𝑙𝑦 remains constant; in contrast, the(𝑅𝑛𝑙 /𝑅0 )𝐸𝑝𝑖 exhibits a clear signature of the SHE contribution. Our results suggest thatthe spin diffusion length of epitaxial platinum exceeds 100 nm.
References[1] M. Morota, Y. Niimi, K. Ohnishi, D.H. Wei, T. Tanaka, H. Kontani, T. Kimura, Y.
Otani, Phys. Rev. B 83 (2011), 174405[2] Zheng Zhu, Magnetic and transport properties in epitaxial platinum and 𝐶𝑜2 𝑀𝑛𝐺𝑎
thin films. The University of Tokyo, 2020, Dissertation[3] C. Chen, D. Tian, H. Zhou, D. Hou, and X. Jin, Phys. Rev. Lett. 122, 016804 (2019).

Spin-orbit and orbital torque in (W or Cr)/CoFeB/MgO stacks for SOTMRAM application
S. Chiba,1,2* Y. Marui,1 H. Ohno,1,3,4,5 and S. Fukami1,2,3,4,5,6
1

Laboratory for Nanoelectronics and Spintronics, RIEC, Tohoku Univ., 2Graduate School ofEngineering, Tohoku Univ., 3WPI-AIMR, Tohoku Univ., 4CSIS, Tohoku Univ.,
5
CIES, Tohoku Univ. 6Inamori Research Institute for ScienceAs a replacement for spin-orbit torque (SOT)1, orbital torque (OT)2 has attracted
significant attention since theoretical predictions that the orbital Hall conductivity could be
one order of magnitude larger than the spin Hall conductivity in heavy metals3,4; the latter has
been intensively studied for SOT-magnetoresistive random access memory (MRAM)5.
However, a systematic study on OT in stacks compatible with the SOT-MRAM application is
missing. Here, we comparatively evaluate SOT and OT in NM (= Cr or W)/CoFeB/MgO
stack compatible with SOT-MRAM application. Note that Cr is expected to generate large
OT, whereas W has been used in SOT-MRAM demonstrations5.
Figure 1(a,b) shows the stack structure of Cr/CoFeB/MgO and W/CoFeB/MgO,
respectively. We varied NM and CoFeB layer thicknesses and evaluated the spin-orbital Halleff
eff
conductivity (𝜎𝐿𝑆) using a harmonic Hall technique. We find that 𝜎𝐿𝑆in Cr/CoFeB/MgO ispositive and increases with increasing Cr and CoFeB thicknesses, consistent with the previous
effreports on OT. Meanwhile, 𝜎𝐿𝑆
in W/CoFeB/MgO shows a cross-over, i.e., a large negativeeff
𝜎𝐿𝑆 is obtained when both W and CoFeB are thin whereas the sign changes to positive withincreasing their thicknesses. These results give a new insight in the material engineering for
SOT-MRAM applications.

References
1.
Shao, Q. et al. Roadmap of Spin–Orbit Torques. IEEE Transactions on Magnetics 57,
1–39 (2021).
2.
Go, D. & Lee, H.-W. Orbital torque: Torque generation by orbital current injection.
Phys. Rev. Res. 2, 013177 (2020).
3.
Tanaka, T. et al. Intrinsic spin Hall effect and orbital Hall effect in 4d and 5dtransition metals. Phys. Rev. B 77, 165117 (2008).
4.
Salemi, L. & Oppeneer, P. M. First-principles theory of intrinsic spin and orbital Hall
and Nernst effects in metallic monoatomic crystals. Phys. Rev. Mater. 6, 095001 (2022).
5.
Natsui, M. et al. Dual-Port SOT-MRAM Achieving 90-MHz Read and 60-MHz Write
Operations Under Field-Assistance-Free Condition. IEEE Journal of Solid-State Circuits 56,
1116–1128 (2021).

コメントの追加 [SF1]: 5 番は SOT-MRAM ではないので引用不要

コメントの追加 [SF2]: 5 番は SOT-MRAM ではないので引用不要
コメントの追加 [SF3]: ここで Natsui を再度引用。

Spin-pumping driven by non-linear harmonic generation
A. Sud1*, T. Dohi2, M. Cubukcu4, K. V. De Zoysa2, Y. Yamane2,3, S. Kanai1, 2, 5,
6, 7, 8, 9
and S. Fukami1, 2, 6, 7
*Presenter
1
WPI-AIMR, Tohoku University, 2-1-1, Katahira, Sendai 980-8577, Japan
2
RIEC, Tohoku University, 2-1-1, Katahira, Sendai 980-8577, Japan
3
FRIS, Tohoku University, Sendai 980-8578, Japan
4
NPL, Hampton Rd, Teddington TW11 0LW, United Kingdom
5
PRESTO, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
6
CSIS, Tohoku University, Sendai 980-8577, Japan
7
Graduate School of Engineering, Tohoku University, Sendai 980-0845, Japan
8
National Institutes for Quantum Science and Technology, Takasaki 370-1207, Japan
9
Division for the Establishment of Frontier Sciences of Organization for Advanced Studies at
Tohoku University, Tohoku University, Sendai 980-8577, Japan
Non-linear systems, which are maintainedin non-equilibrium steady states, host a wide
range of functionally relevant properties thatcannot be realized in thermal equilibrium. A
common situation occurring in non-linear
media is the simultaneous excitation andinteraction of many non-coherent oscillatory
degrees of freedom, where the energy
distribution of these degrees of freedom giverise to multitude of physical phenomena suchas phase-transitions and bistability [1]. In asystem when sub-harmonic and secondharmonic modes are coherently excited, then
1. Color map showing the ISHE voltage
the two generation processes can compete. For Fig
obtained as a function of frequency and applied
certain excitation amplitude the system enters in a field. When optical mode frequency is twice of
acoustic mode (~7 GHz), the optical mode
bistable regime [2].
bifurcates into two branches with opposite polarity.
In this work we demonstrate the effect of such The inset shows the mode bifurcation.
non-linear interaction of sub and second harmonicmodes on the spin-pumping. The system we use is a multi-layer structure of two ferromagnetic
layers separated by a non-magnetic spacer (CoFeB/Ru/CoFeB). The microwave field, h wasused to resonantly excite two modes (acoustic and optical) which induced a spin current inneighboring metal (Ta) that was detected through inverse spin-Hall effect (ISHE). For certain
microwave amplitude, an enhancement is seen in spin current for optical mode at 2f frequency
with a discontinuity (Fig.1) and the mode bifurcates into two branches with opposite polarity
showing phase transition.
Acknowledgements: This research received funding from JSPS Postdoctoral fellowship(P21777) and JSPS Kakenhi (22F21777).
References[1] H. Pan et al., Phys. Rev. B 106, 054425 (2022).
[2] R.C. Shen et al., Phys. Rev. Lett. 129, 123601 (2022).

Title: Nonlinear optical response of a s-wave superconductor NbN
with using terahertz vortex beam
K. Tanaka1*, F. Sekiguchi2, N. Yoshikawa1, and R. Shimano1, 2*Presenter
1
Department of Physics, The University of Tokyo, Japan
2
Cryogenic Research Center, The University of Tokyo, Japan
Abstract (up to 200 words)
In superconductors, an amplitude fluctuation of the superconducting order parameter called
Higgs mode exists with its energy located around the superconducting gap 2. While theexperimental observation of the Higgs mode has long been elusive over decades, recent
terahertz (THz) nonlinear spectroscopy has revealed its presence experimentally by theintense THz pulse-induced quench experiments [1], and the THz pulse drive experiments [2].
In the latter case, Higgs-mediated THz third harmonic generation (THG) was observed
revealing the nonlinear coupling between Higgs mode and the electromagnetic field [2].
In this study, we investigated the interaction of the Higgs mode with a THz vortex beam
which possesses a spiral phase front and carries orbital angular momentum. We performed
THz pump – THz probe spectroscopy in a s-wave superconductor Niobium nitride (NbN).
Based on the experimental results, we will discuss the coupling between Higgs mode and THz
vortex beam.
References[1] R. Matsunaga, Y. I. Hamada, K. Makise, Y. Uzawa, H. Terai, Z. Wang, and R. Shimano,
Higgs Amplitude Mode in the BCS Superconductors Nb_{1−x}Ti_{x}N Induced by
Terahertz Pulse Excitation, Phys. Rev. Lett. 111, 057002 (2013).
[2] R. Matsunaga, N. Tsuji, H. Fujita, A. Sugioka, K. Makise, Y. Uzawa, H. Terai, Z. Wang,
H. Aoki, and R. Shimano, Light-Induced Collective Pseudospin Precession Resonating with
Higgs Mode in a Superconductor, Science 345, 1145 (2014).

Title: Quantum-classical correspondence and dissipative todissipationless crossover in magneto-transport phenomena
A. Yamada1,2*, Y. Fuseya1*Presenter
1
University of Electro-Communications Tokyo, Chofu, Tokyo 182-8585, Japan
2
Institute of Solid-State Physics, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
Abstract
Classical transport formula must be modified when the effect of Landau quantizationis remarkable. In previous research [1,2,3], a general representation of magneto-transporttensors was derived and the effects of several types of scattering in semiconductors werestudied precisely. However, correspondence between classical and quantum theory inarbitrary magnetic fields has not been obtained.
We derived a magneto-conductivity tensor based on the Landau quantization in freeelectrons. The correspondence to the classical theory is apparent in our representation [4].
Although it includes microscopic parameters, they can be renormalized into the macroscopic
observables. Hence, parameter fitting is accessible and applicable to the analysis ofexperiments. Quantum effects are renormalized into the oscillation in the diagonalcomponents.
A remarkable point is that the Hall conductivity shows a crossover from nonequilibrium to equilibrium transport because the non-equilibrium component is canceled with
one of the equilibrium terms (Fig.1). In other words, the magneto-conductivity is nondissipative at a high field limit. This equilibrium transport has a common origin with thequantum Hall effect in two-dimensional systems [5]. We pointed out that the crossover isobservable as the phase shift of quantum oscillation in three-dimensional semimetals, while
the quantization of Hall conductivity is unexpected.

(Fig.1) Contributions to each component
in magnetoconductivity tensor

References[1] H. Shiba, et al., J. Phys. Soc. Jpn. 30, pp. 972-987 (1971).
[2] T. Ando and Y. Uemura. Journal of the Physical Society of Japan, 36(4) (1974).
[3] A. A. Abrikosov. Sov. Phys. JETP, 29(4) (1969).
[4] A. Yamada and Y. Fuseya, arXiv:2307.00763v1 (2023)[5] D. J. Thouless, et al., Phys. Rev. Lett. 49, 405 (1982)

Superconductivity in Hole-Doped Perovskite Hydride KMgH3
Shaocong Lu1*, Ryosuke Akashi2, and Shinji Tsuneyuki1*Presenter
1
Department of Physics, The University of Tokyo, Japan
2
National Institutes for Quantum Science and Technology, Japan
In our work, the stability and superconductivity of hole-doped perovskite hydride KMgH3
with varying lattice parameters, corresponding to different pressures, are studied from firstprinciples. KMgH3 is a stable perovskite hydride [1], and it has relatively strong lattice
vibrations and a peak in the density of states just below Fermi level, making it a promising
candidate for high-temperature superconductivity after hole-doping. We applied uniform hole
doping to KMgH3, which leads to a larger density of states at Fermi level as the doping
concentration gets larger. Lattice anharmonicity was treated by means of the self-consistentphonon (SCPH) method implemented in ALAMODE [2][3]. Firstly, we studied the stabilityof the doped compound, and we found that the doped compound gradually loses its
mechanical stability with shrinking cell and increasing doping concentration, butanharmonicity considerably contributes to restoring the stability. After the investigation of thestability, calculations of electron-phonon coupling strength 𝜆 was carried out, and thesuperconducting transition temperatures was estimated for different pressures and doping
concentrations.

References[1] Richard Schumacher and Alarich Weiss. Kmgh3 single crystals by synthesis from theelements. Journal of the Less Common Metals, 163(1):179–183, 1990.
[2] T. Tadano, Y. Gohda, and S. Tsuneyuki, J. Phys.: Condens. Matter 26, 225402 (2014).
[3] T. Tadano and S. Tsuneyuki, Phys. Rev. B 92, 054301 (2015).

Title:Developing Innovative Hard X-ray Spectral Imager for Studies ofParticle Acceleration in Solar Flares
Shunsaku Nagasawa1,2*, Takahiro Minami1,2, Shin Watanabe3,2,
and Tadayuki Takahashi2, 1*Presenter
1: Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
2: Kavli IPMU (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan
3: ISAS/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan

Abstract (up to 200 words)
For understanding the particle acceleration in various scale plasma environments by
the release of magnetic energy through magnetic reconnection, solar flares are uniqueobservational targets in that they are bright in multi-wavelength and spatially resolvable.
Focusing Optics X-ray Solar Imager (FOXSI) is the solar-dedicated X-ray sounding rocket
mission to realize the direct imaging method combined with Wolter-I focusing optics andfine-pitch focal plane detectors. The fourth flight FOXSI-4 [1], scheduled in April 2024, aims
to realize the world’s first imaging spectroscopic observation of mid-large class solar flares,
while the past three flights targeted the relatively quiet regions of the Sun. Our group is
responsible for developing hard X-ray focal plane detectors. To meet the new requirementsfor observing solar flares, we developed a wide-gap CdTe semiconductor double-sided strip
detector (CdTe-DSD) [2]. We seamlessly evaluated performance and developed response
functions, simulations, and data acquisition systems.
In this presentation, we will give an overview of the FOXSI experiment, details of thewide-gap CdTe-DSD, and the status of preparations for FOXSI-4 for the launch in Apr 2024.
References[1] JC Buitrago-Casas et al., Proc. SPIE, 2021, vol 11821, 210.
[2] S. Nagasawa, et al. NIMA, 2023, vol 1050, 168175.

Fig. Schematic diagram of FOXSI payload (Image Credit: FOXSI-3 team)Title: Observation of Spin Hall Conductivity Spectrum of GaAs in
the Terahertz Frequency Regime
T. Fujimoto1*, T. Kurihara1, Y. Murotani1, T. Tamaya1, N. Kanda1,2, C. Kim1, J.
Yoshinobu1, H. Akiyama1, T. Kato1, and R. Matsunaga1*Presenter
1
The Institute for Solid State Physics, The University of Tokyo, Japan2

Ultrafast Coherent Soft X-ray Photonics Research Team, RIKEN Center for Advanced

Photonics, RIKEN, Japan

Abstract (up to 200 words)
In the spin-orbit coupled systems, the carrier flow under a bias field is deflected intotransverse directions dependent on their spins due to the Berry-curvature mechanism or
impurity scattering, resulting in the spin current. This is known as the spin Hall effect (SHE)[1]. The SHE and its reciprocal process, the inverse spin Hall effect (ISHE), are crucial
ingredients for the conversion between charge current and spin current in spintronics. However,conventional quasi-static measurements have difficulty revealing their microscopic
mechanisms. What is essential is the information on dynamics faster than the impurity
scattering rate, which typically lies on the terahertz (THz) frequency regime.
In this presentation, we report the first observation of the spin Hall conductivity
spectrum of GaAs by THz polarimetry with a near-infrared (NIR) pump pulse [2]. After the
spin injection by the NIR pump, our highly precise THz polarimetry detects the Faraday rotation
due to the ISHE. The obtained spin Hall conductivity spectrum shows an excellent agreementwith theories [3], demonstrating a crossover in the dominant origin from impurity scattering in
the dc regime to the Berry-curvature mechanism in the THz regime. Our THz-spectroscopic
approach paves the way to clearly resolve microscopic mechanisms of the SHE.
References[1] J. Sinova et al., Phys. Rev. Lett., 92, 126603, (2004).
[2] T. Fujimoto et al., arXiv:2305.09155 (Phys. Rev. Lett. in press).
[3] P. Nozières and C. Lewiner, J. Phys. (Paris) 34, 901 (1973).

Hiroto Saito
We have developed an efficient method for accurately calculating magnetic anisotropy.
This method involves creating a Wannier basis tight-binding model using first-principles
calculations and considering the crystal and spin symmetry. Furthermore, this approach
employs time-reversal symmetry to distinguish magnetization from spin-orbit
interactions, making it easy to generate Hamiltonians with magnetization oriented in any
direction without requiring additional DFT calculations each time.
To validate our method, we apply it to calculate the magnetocrystalline anisotropy energy(MCAE) of L1_0-type FePt and FeNi. Our results show excellent agreement withprevious studies on the chemical potential dependence of the MCAE. Additionally, we
obtain the full angle dependence of the MCAE on the direction of magnetization. Thesefindings provide a deeper understanding of magnetic properties and offer potential
applications in various fields.

Magnetic studies of epitaxial thin films of noncollinear Weyl
antiferromagnet Mn3Sn
K. Gas1*, S. Wakabayashi2,3, T. Uchimura2,3, J.-Y. Yoon2,3, Y. Takeuchi4,5,
S. Kanai1,2,3,4,6,7,8, M. Sawicki9, H. Ohno1,2,4,10, and S. Fukami1,2,3,4,10
1

Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
Laboratory for Nanoelectronics and Spintronics, RIEC, Sendai, Japan
3
Graduate School of Engineering, Tohoku University, Sendai, Japan
4
WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
5
National Institute for Materials Science, Tsukuba, Japan
6
PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Japan
7
Division for the Establishment of Frontier Sciences of Organization for Advanced Studies at
Tohoku University, Tohoku University, Sendai, Japan
8
National Institutes for Quantum Science and Technology, Takasaki, Japan
9
Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
10
Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan* Presenter, e-mail: gas.katarzyna.a2@tohoku.ac.jp
2

Non-collinear antiferromagnetic (AFM) Mn3Sn has shown highly advantageous FM-like
properties [1,2]. The spin structure of Mn3Sn is the result of a fine balance between several
different interactions, therefore, even minute structural changes will have a great impact.
Magnetometry is an indispensable investigation tool here, however due to nearly perfectmoment cancelation of the AFM thin layers their magnetic signals are at the verge of practicaldetection limits of standard volume magnetometry. The unavoidable presence of bulky
substrates, supporting the thin films, additionally strongly confuses the response of Mn3Sn
layers.
We present results of magnetometry studies obtained for epitaxial Mn3Sn(t) layers
deposited by magnetron sputtering on MgO(110) single-crystal substrates (10 nm < t < 100nm) [3]. Firstly, we show a practical method of elimination of the spurious magnetic signalsof MgO. We achieve this by adopting the concept of in situ compensation, elaborated
previously to mitigate contributions brought about by bulky substrates [4]. Secondly, we
present and discuss the thickness dependence of the spontaneous magnetization and criticaltemperatures. We find that all these characteristics correlate with the lattice parameter.
Finally, we present comparison between results of magnetometry and of anomalous Hall
effect.
[1] S. Nakatsuji et al., Nature, 527 (7577), 212 (2015).
[2] Y. Takeuchi et al., Nat. Mater. 20, 1364-1370 (2021).
[3] J. -Y. Yoon et al., AIP Adv. 11, 065318 (2021).
[4] K. Gas and M. Sawicki, Meas. Sci. Technol. 30, 085003 (2019).
Acknowledgements: This study has been partly supported by TUMUG Support Programfrom Center for Diversity, Equity, and Inclusion, Tohoku University, and by JSPS Kakenhi
19H05622, 21J23061, 22K14558, and 22KK0072.

Title: 3D Topological insulator in a strong magnetic field
Hiroyuki Sudo1*, Takashi Oka 1*Presenter
1

The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan

Abstract
Magnetic fields have significantly influenced the landscape of condensed matter physics,
particularly in terms of electronic properties. Especially, the quantum hall effect highlighted the significanceof topology in condensed matter [1]. Nowadays, with the development of moiré materials and high magnetic
field environments, the relationship between topology and magnetic fields has received renewed attention.
Especially, both theoretical and experimental attention has been focused on the occurrence of gap-closing
behavior in the topological insulator at high magnetic fields, reflecting the absence of symmetric,
exponentially localized Wannier functions in topological insulators [2-4]. In this poster presentation, we
focus on the behavior of 3D topological insulators (3D Bernevig-Hughes-Zhang model) in strong magnetic
fields and report some chiral separation effects [7] in the vicinity of gap-closing magnetic flux.

References[1] D. J. Thouless, M. Kohmoto, M. P. Nightingale, and M. den Nijs, Phys. Rev. Lett. 49, 405 (1982).
[2] B. Lian, F. Xie, and B. A. Bernevig, Phys. Rev. B 102, 041402(R) (2020).
[3] J. Herzog-Arbeitman, Z.-D. Song, N. Regnault, and B. A. Bernevig, Phys. Rev. Lett. 125, 236804 (2020).
[4] G. W. Burg et al., arXiv preprint arXiv:2006.14000 (2020).
[5] V. A. Miransky and I. A. Shovkovy, Phys. Rep. 576, 1 (2015).

Ti-Doping Effect in Weyl Antiferromagnet Mn3Sn:
Zhiyi DuanA,*, Mingxuan FuA, Shunichiro KurosawaA, Daisuke Nishio-HamaneB, Akito SakaiA,and Satoru NakatsujiA, B, C*

Presenter
Department of Physics, University of Tokyo, Japan
B
ISSP, University of Tokyo, JapanC
Department of Physics and Astronomy, Johns Hopkins University, USAA

Topological antiferromagnets has been considered promising candidates in spintronics becauseof their intrinsic properties including superfast spin dynamics and elimination of stray fields[1]. In particular, Mn3Sn has attracted much attention for its special triangular AFM spin
configuration in the Kagome plane, showing evidence of Weyl points near the Fermi surface[2]. We here present our results of spin texture tuning by introducing Ti atoms as dopant into
this system while keeping the lattice structure. Approx. 10% Mn-site doped single crystals with𝑇𝑁 ≈ 395𝐾 is acquired. Our doped samples show modified magnetic properties and strongly
anisotropic electrical transport behavior. With such findings, we can expect better tuning ofmagnetic properties and strength of electron interactions, and thus gaining deeper
understanding in the role of band topology, magnetism and correlated effects in such doped
systems.

Reference:[1] A. Hirohata et al., J. Magn. Magn. Mater. 509, 166711 (2020)[2] S. Nakatsuji, N. Kiyohara and T. Higo, Nature 527, 212 (2015)

Title: The Status of the Simons Array Experiment and the Science
Cases with Circular Polarization Measurements
Kana Sakaguri 1*, and POLARBEAR/Simons Array Collaboration*Presenter
1
The University of Tokyo, Japan

Abstract (up to 200 words)
Observations of mm-wave polarization provide rich information in understanding the universe[1, 2]. Circular polarization can explore beyond-the-standard-model signals such as galactic
synchrotron emission, which is intrinsically circularly polarized, faraday conversion by
Population (Pop) 3 stars, Lorentz violation, and others. However, accurate observation of
circular polarization is challenging, and only little has been studied because the signals are
estimated to be very small. The Simons Array (SA), an ongoing experiment on the Atacama
plateau in Chile, aims to measure polarizations accurately. The second telescope achieved thefirst light recently. In this poster, we discuss the status of the SA and science cases with thecircular polarization measurements.
[1] U. Seljak, M. Zaldarriaga, Phys. Rev. D 60, 043504 (1999)[2] M. Kamionkowski, A. Kosowsky, A. Stebbins, Phys. Rev. Lett. 78, 2058 (1997)

Title: Magnetic imaging of quantum vortices in microfabricatedsuperconductor using diamond quantum sensor
Shunsuke Nishimura1, Taku Kobayashi1, Daichi Sasaki1, Takeyuki Tsuji2,
Takayuki Iwasaki2, Mutsuko Hatano2, Kento Sasaki1, Kensuke Kobayashi1*Presenter
1
Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan2
Department of Electrical and Electronic Engineering, School of Engineering, Tokyo Instituteof Technology, Meguro, Tokyo 152-8552, Japan

Field (µT)

Abstract
Superconductors exhibit a phenomenon known as quantum vortices due to thequantization of magnetic flux penetrating them [1]. These vortices are significant for their
pairing symmetry and electromagnetic response near transition points, and have been studied
using various visualization methods. Recently, a novel measurement approach utilizing
nitrogen-vacancy (NV) centers in diamonds, known as quantum diamond microscopy (QDM),
has emerged, garnering attention as a probe for magnetic field distribution. This method offers
access to previously elusive information, such as the quantification of flux density and its
fluctuation [2].
In this research, we apply this method to measure70
quantum vortices in a high-Tc superconductor,
YBa2Cu3O7-δ thin film, using a thin sensor layer of NV
ensembles [3], which are all aligned to the surface. We
35
obtained a quantitative magnetic image of the stray fieldaround quantum vortices, over a broad field of view [4].
Furthermore, we determine the temperature dependence
B = 60 µTof the magnetic penetration depth from field distribution
0
around vortex, replicating findings from previous
Figure. Imaging of stray field distribution
research.
quantum vortices on YBa2Cu3O7-δ thin
Our approach demonstrates broad applicability aroundfilm. This device is fabricated in the shape of aespecially to superconducting quantum vortices under Hall bar, and the superconductor corresponds tovarious conditions, supporting the use of QDM for the rectangular area in the center of the figure.
exploring physical properties under severe conditions. In this presentation, we also show
results on a microfabricated superconductor hall device (see Figure) as a basis formeasurements of vortex dynamics.
FC

References[1] C. C. Tsuei and J. R. Kirtley, Rev. Mod. Phys. 72, 969 (2000).
[2] F. Casola et al., Nat. Rev. Materials 3, 17088 (2018).
[3] T. Tsuji et al., Diam. Relat. Mater. 123, 108840 (2022).
[4] S. Nishimura et al., Appl. Phys. Lett. 123, 112603 (2023)

Antiferromagnetic magnonic charge current generation via
ultrafast optical excitation
Lin Huang1*, Liyang Liao2, Hua Bai1, Feng Pan1, and Cheng Song1
1

Key Laboratory of Advanced Materials (MOE), School of Materials Science andEngineering, Tsinghua University, Beijing, China.
2

Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan.

Abstract
Néel spin-orbit torque (NSOT) allows a charge current pulse to efficiently manipulate
the Néel vector in antiferromagnets, which offers a unique opportunity for ultrahigh density
information storage with high speed. However, the reciprocal process of Néel spin-orbit
torque, the generation of ultrafast charge current in antiferromagnets has not been
demonstrated. Here, we report the experimental observation of charge current generation in
antiferromagnetic metallic Mn2Au thin films using ultrafast optical excitation. The ultrafast
laser pulse excites antiferromagnetic magnons, resulting in instantaneous non-equilibrium
spin polarization at the antiferromagnetic spin sublattices with broken spatial symmetry. This
staggered spin polarization of the electrons is directly converted into a charge current by spinorbit coupling due to the local inversion symmetry breaking. The magnonic charge current
can be expressed as, where the charge current J and spin polarization σA,B are
orthogonal. The observed AFM magnonic charge current generated from the magnetic
moment fluctuation can be a favorable building block for antiferromagnetic THz emitter andprovides a promising platform to deepen the understanding of NSOT from the view ofOnsager reciprocity. Besides the fundamental significance on the Onsager reciprocity, theobserved magnonic charge current generation in antiferromagnet would advance thedevelopment of antiferromagnetic THz emitter.

Figure Principle of magnonic charge current generation in Mn2Au and Experimental setup
and THz spectrum.
References[1] Chen, X. et al. Electric field control of Néel spin–orbit torque in an antiferromagnet. Nat. Mater.
18, 931–935 (2019).
[2] Železný, J. et al. Relativistic Néel-order fields induced by electrical current in antiferromagnets.
Phys, Rev. Lett. 113, 157201 (2014).

Title: Stochastic Reaction-Diffusion System of Biological
Chemical Reaction Network
Y, Watanabe1, 3*, Z. Jeandupeux2*，Y. Ishiguro3，T. Oka3，M. Udagawa4，and S. Takayoshi5*Presenter
1
University of Tokyo, Japan
2
Swiss Federal Institute of Technology in Lausanne, Switzerland
3
The Institute of Solid State Physics, Japan
4
Gakushuin University, Japan
5
Konan University, Japan
Abstract (up to 200 words)
Biological reaction systems are non-equilibrium open many-body systems, which sharesimilarities with quantum many-body systems in which electrons and spins interact intricately.
Based on this point, it is known that a stochastic quantum many-body system can be definedfrom a chemical reaction network (CRN) [1, 2]. In other words, the properties of CRNs can beunderstood by analyzing the corresponding non-Hermitian Hamiltonians. In this study, wedefine a non-Hermitian Hamiltonian from the cAMP-producing system, which is responsible
for the regulation of gene transcription, and provide a basis for numerical investigation of the
dynamics of the system.

References[1] M. Doi, J. Phys. A 9, 1465 (1976).
[2] L. Peliti, J. Phys. France. 46, 1469-83 (1985).

Magnetic Raman spectroscopy for Majorana edge states inKitaev spin liquids
Yuki Yamazaki1*, Shingo Kobayashi2, and Akira Furusaki1, 2*Presenter
1 RIKEN Cluster for Pioneering Research (CPR), Wako, Saitama 351-0198, Japan
2 RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198,
Japan
The Kitaev honeycomb model can be mapped to a free Majorana fermion (MF)system [1]. The ground state is characterized by the itinerant MFs with a uniform Z2gauge field. Depending on the anisotropy of the exchange interactions, the groundstate has the two topologically distinct phases (the A and B phase).
We study the magnetic Raman spectra [2,3] for the Majorana edge state (MES) in the
A phase. Firstly, the flat band of MES acquires the sine curved dispersion when amagnetic field is applied. Then, we find the Raman intensity is enhanced by the Van
Hove singularity in the dispersion of MES. Secondly, we consider the situation where
the MESs at both edges are correlated due to the finite size effect. We reveal that thecorrelation of the MESs strongly depends on the anisotropy of the exchangeinteractions, and the resulting correlation also changes the frequency dependence ofthe magnetic Raman spectra. These results are different from the MES in the B phase[4] and present a unique signature of the MES in the A phase.
[1] A. Kitaev, Ann. Phys. 321, 2 (2006).
[2] J. Knolle, Gia-Wei Chern, D. L. Kovrizhin, R. Moessner, and N. B. Perkins, Phys.
Rev. Lett. 113, 187201 (2014).
[3] L. J. Sandilands, Y. Tian, K. W. Plumb, and Y.-J. Kim, and K. S. Burch, Phys.
Rev. Lett. 114, 147201 (2015).
[4] J. J. He and N. Nagaosa, Phys. Rev. B 103, L241109 (2021).

1

X-ray magnetic circular dichroism arising from the magnetic
dipole moment in Mn3Sn and Mn3Ir
K. Kurita and T. Koretsune*
Department of Physics, Tohoku University, Japan
Recently, there has been considerable interest in antiferromagnetic materials that have magnetic
symmetry compatible with the ferromagnetic state. In such materials, physical properties thatwere known to be specific to ferromagnets are observed. Here, we focus on one of such
examples, the X-ray magnetic circular dichroism (XMCD) spectra for noncollinear
antiferromagnets, Mn3Sn and Mn3Ir. By employing the differential form of the sum rules, wetheoretically evaluate the XMCD spectra from first principles. We decompose the origin of the
XMCD spectra into the contributions of spin magnetic moment, orbital magnetic moment, andmagnetic dipole moment, and find that the contribution of magnetic dipole moment is dominant
in these materials. We discuss that the cancellation of the contribution of spin magnetic moment
comes from the symmetry in the case without spin-orbit couplings[1].
References[1] K. Kurita and T. Koretsune, J. Phys. Soc. Jpn. accepted.

Title: Charge-spin conversion in antiferromagnetic RuO2
H. Bai1*, C. Song1, and F. Pan1
*Presenter
1
Tsinghua University, Beijing, China, 100084
Abstract (up to 200 words)
The relativistic spin Hall effect (SHE) and inverse spin Hall effect (ISHE) enable the efficient
generation and detection of spin current. Nevertheless, the spin polarization is limited to thedirection orthogonal to both charge and spin current. In contrast, a novel relativistic mechanismof spin-charge conversion, termed as altermagnetic spin splitting effect (ASSE), wastheoretically predicted. [1,2] This poster presents experimental evidence of SST and the inverse
effect in collinear antiferromagnetic RuO2 films. First, according to spin torque ferromagnetic
resonance (ST-FMR) measurements of RuO2 films, we exhibit that spin current direction iscorrelated to the crystal orientation of RuO2 and spin polarization direction is parallel to the
Néel vector, indicating the existence of SST in RuO2. [3] Second, based on spin Seebeck effectand THz emission measurements, we demonstrate that inverse ASSE can convert spin current
polarized along Néel vector into charge current, which manifests as Néel vector-dependent spin
Seebeck voltage signals and THz emission signal. [4,5] These findings not only present a newmember for the spin torques besides traditional STT and SOT, but also proposes RuO2 for bothpromising spin source and spin sink in spintronic devices.
References[1] M. Naka, et al., Nat. Commun. 10, 4305 (2019).
[2] R. González-Hernández, et al., Phys. Rev. Lett. 126, 127701 (2021).
[3] H. Bai, et al., Phys. Rev. Lett. 128, 197202 (2022).
[4] H. Bai, et al., Phys. Rev. Lett. 130, 216701 (2023).
[5] Y. Liu, H. Bai et al., Adv. Opt. Mater. 2300177 (2023).

Detection of magnetic octupolar orderby nonlinear magnetoelectric effectJun Oike*, Koki Shinada, and Robert Peters
Department of Physics, Kyoto University, Japan

Emergence of ordered states associated with symmetry lowering has brought much diversity tocondensed matter physics, one of which is multipolar order. For example, antiferromagnets with
time-reversal symmetry breaking such as Mn3Sn [1] and all-in all-out pyrochlore Iridates [2] haveclustered magnetic octupolar order. Altermagnets such as RuO2 and MnF2 have been also
considered to have magnetic octupolar order [3].
On the other hand, methods for directly observing and controlling higher-order multipoles arestill in their infancy. One of them is to use response phenomena from Neumann’s principle. For
example, the linear magneto-optic Kerr effect has been successfully used to control the domain
for magnets due to activated magnetic dipoles. However, it must be extended to nonlinear
responses for materials where lower-order multipoles are inactive and higher-order ones are active[4][5].
In this study, we propose the nonlinear magnetoelectric effect as a probe of magnetic octupolarorder. Specifically, we perform model calculations of the nonlinear magnetoelectric tensor for
pyrochlore substances and RuO2 with the lowest-ranked magnetic octupoles. This study not only
provides a new probe of magnetic octupoles, but also encourages the use of nonlinear responses toinvestigate multipolar order experimentally.

References[1] S. Nakatsuji, et al., Nature 527, 212 (2015).
[2] K. Ueda, et al., Nat. Commun. 9, 3032 (2018).
[3] S. Bhowal and N. A. Spaldin, arXiv:2212.03756v1.
[4] A. Sorn and A. S. Patri, arXiv:2311.03435v1.
[5] Y. Fang, et al., arXiv:2310.11489v1.

Title: Effect of Y-doping on the high-temperature antiferromagnet
Ba5Co5ClO13
P. K. Tung1,2*, Z. Lei2, L. M. Wang 2, S. Nakatsuji1,3,4,5*Presenter
1
Department of Physics, The University of Tokyo, Japan2

Department of Physics, National Taiwan University, Taiwan

3

The Institute for Solid State Physics, the University of Tokyo, Japan

4

Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins
University, USA
5

Trans-Scale Quantum Science Institute, The University of Tokyo, Japan

Abstract (up to 200 words)
This study explores the potential for inducing superconductivity in a compound with highantiferromagnetism. The quest for unconventional superconductivity in high-temperature
antiferromagnet has attracted extensive research interests [1], and our investigation aims todiscover something new from the specific antiferromagnet.
Here, we investigate the effects of Y doping into Ba5Co5ClO13, characterized by hightemperature antiferromagnetism with a Neel temperature of 135 K [2][3]. The primary objective
is to suppress its antiferromagnetic order and explore the possibility of realizing
unconventional superconductivity by systemically changing the lattice size. For this purpose,
we selected Y as the dopant, whose ionic radius is similar to Ba. By combining single-crystal
X-ray diffraction (XRD) with magnetic and electrical transport measurements, we obtain new
insights into the connection between structural properties and antiferromagnetism in
Ba5Co5ClO13 under controllable doping.

References[1] P. Monthoux, A. V. Balatsky, and D. Pines. Phys. Rev. B 46, 14803 – Published 1
December 1992
[2] Wang, H., Yang, J., Zhang, Z., Dong, C., and Fang, M. Phys. Lett. A (2009), 373, 4092
[3] K. Yamaura, D.P. Young, T. Siegrist, C. Besnard, C. Svensson, Y. Liu, R.J. Cava J. Solid
State Chem., 158 (2001)

Fabrication of tunnel junction with the antiferromagnetic Weyl
semimetal Mn3Sn dot down to sub-micron scale
M. Yunokizaki1, R. Kondo1, H. Idzuchi1,2, K. Inukai3, S. Sakamoto2, K. Tanaka1, T. Higo1,2,4,
S. Miwa2,4,5, S. Nakatsuji1,2,4,5,6
1

School of Science, University of Tokyo, Japan
ISSP, University of Tokyo, Japan3
JSR Corporation, Japan
4
JST-CREST, Japan
5
TSQS, University of Tokyo, Japan
6
IQM, Johns Hopkins University, USA
2

Antiferromagnetic spintronics has attracted much attention in recent years because of its
potential for ultrafast magnetization dynamics, robustness against magnetic field perturbations,and the absence of stray fields [1-3]. While various methods exist for electrically detecting
AFM order, efficient detection, particularly at submicron scale, has remained elusive. Recently,
magnetic tunnel junctions based on non-colinear antiferromagnets such as Mn3Sn [4] and Mn3Pt[5] have been reported. These may be used to efficiently detect antiferromagnetic states,
potentially much larger voltage signal than the anomalous Hall effect found in theantiferromagnetic Weyl semimetals [6]. The junction size in our previous report was 10 μm 2[4]. In this study, we successfully reduced the junction size to ~0.3 μm2 in an Fe/MgO/Mn3Sn
MTJ.
The multilayer films were prepared using molecular beam epitaxy and sputtering. Distinct
magnetization switching processes for Mn3Sn and Fe were observed as revealed by themagneto-optical Kerr effect (Fig.1a). The magnetic tunnel junctions were fabricated using
electron beam lithography and Ar ion etching (Fig.1b). Magnetoresistance was observed at thefields corresponding to expected magnetization reversal. These results enable further studies
for the magnetization process in sub-micron Mn3Sn dots and pave the way for developing
antiferromagnetic device application.
References[1] A. MacDonald and M. Tsoi, Philos. Trans. A Math. Phys. Eng. Sci. 369, 3098 (2011).
[2] B. G. Park et al. Nat. Mater. 10, 347 (2011).
[3] S. Nakatsuji and R. Arita, Annu. Rev. Condens. Matter Phys. 13, 119 (2022).
[4] X. Chen et al., Nature 613, 490 (2023).
[5] P. Qin et al., Nature 613, 485 (2023).
[6] S. Nakatsuji, N. Kiyohara and T. Higo. Nature 527, 212-215 (2015).
(a)

(b)

Figure 1 (a) Magnetization hysteresis curve of Fe/MgO/Mn3Sn film measured
using magneto-optical Kerr signal. (b) Schematic of the magnetic tunnel junction.

Data-driven self-calibration of quantum circuits
M. Dall’Arno1*, F. Buscemi2*Presenter
1
Department of Computer Science and Engineering, Toyohashi University of Technology, Japan
2
Graduate School of Informatics, Nagoya University, JapanAny circuit is in one-to-one correspondence with a logical table that specifies, upon any
given input state, what the output state of the ideal circuit should be. Since classical states are
perfectly distinguishable in principle, at least at a fundamental level the calibration ofclassical circuits does not therefore present any difficulty. This is in stark contrast with thequantum case where, due to the existence of superposition of states, neither input nor output
states can in general be jointly distinguished perfectly, thus rendering the calibration ofquantum circuits a problem in principle.
Here, we address this fundamental issue by adopting a Bayesian approach to thecalibration of quantum circuits that is data-driven, i.e. it avoids any assumption on thequantum description of the states input and output of the circuit, and solely relies oncorrelations between their classical labels, thus de facto representing a self-calibration of thecircuit. In particular, our approach automatically inherits from Bayes theorem an Occam’s
razor-like minimality criterion that favors the simplest inference that is consistent with theobservations. We show that data-driven self-calibration is equivalent to a particular clustering
problem in the correlation space that can be solved adopting John’s theory on minimum
volume enclosing ellipsoids.
References[1] M. Dall’Arno, On the role of designs in the data-driven approach to quantum statistical inference,arXiv:2304.13258.

[2] M. Dall’Arno, F. Buscemi, A. Bisio, and A. Tosini, Data-Driven Inference,
Reconstruction, and Observational Completeness of Quantum Devices, Phys. Rev. A 102,062407 (2020).
[3] M. Dall’Arno and F. Buscemi, Data-Driven Inference of Physical Devices: Theory and
Implementation, New J. Phys. 21, 113029 (2019).
[4] M. Dall’Arno, S. Brandsen, F. Buscemi, and V. Vedral, Device-independent tests ofquantum measurements, Phys. Rev. Lett. 118, 250501 (2017).
[5] F. John, Extremum problems with inequalities as subsidiary conditions, in Studies andEssays Presented to R. Courant on his 60th Birthday, 187–204, (Interscience Publishers, New
York, 1948).

Tingyu Zhang
Spin transport phenomena at strongly-correlated interfaces play central roles infundamental physics as well as spintronic applications. In this presentation we talkabout the spin tunneling and the shot noise in an itinerant Fermi gas. We investigate
the spin current induced by quasiparticle and spin-flip tunneling processes byapplying a two-terminal model. The interaction dependence of the spin current
indicates an enhanced magnon tunneling in the strong-coupling regime, and acharacteristic behavior around the critical repulsive strength for ferromagnetic phasetransition at low temperatures.
To anatomize spin-transport carriers, we propose the detection of the spin current
noise in interacting itinerant fermions. The Fano factor given by the ratio between thespin current and its noise reflects elementary carriers of spin transport at the interfaceof spin-polarized Fermi gases realized in ultracold atoms. The change of the Fanofactor microscopically evinces a crossover from the quasiparticle transport to magnon
transport in itinerant fermionic systems.

Thermal Hall measurements to detect spontaneous thermal Hall
effect in kagome superconductor CsV3Sb5
H. Yoshida1*, J. Yan1, H. Takeda1, M. Yamashita1, Y. M. Oey2, B. R. Ortiz2,3,
and S. D. Wilson2
1

Institute for Solid State Physics. University of Tokyo., Japan
University of California. Santa Barbara., United States
3
Oak Ridge National Lab., United States
2

Chiral superconductivity, breaking time-reversal symmetry, has attracted attentions as a
topological superconductor characterized by bulk quasiparticle bands with non-trivial
topological numbers.
Experimentally, some candidates of chiral superconductors are suggested mainly by µSR
and Kerr effect measurements [1,2]. However, these methods have difficulties in quantitativeevaluations, and lacking considerations from a topological perspective.
Focusing on topological properties, we propose thermal Hall measurements as a newexperimental approach. In chiral superconductivity, it is theoretically expected thatquasiparticles carrying heat can be observed
as a spontaneous thermal Hall effect at thezero field [3]. By performing spontaneous
thermal Hall measurements, we expect toenable the direct observation of the Chern
number that reflects the topological nature,advancing towards quantitative verification
with theory.
In this poster, we report our trials to detect
the spontaneous thermal Hall effect in the
kagome superconductor CsV3Sb5. For thesuperconducting state in kagome lattices,
unconventional superconductivity such as
extended s-wave, chiral p-wave, and chirald-wave has been theoretically predicted [4].
Indeed, the potential realization of chiralsuperconductivity in this compound has been
Fig1. The temperature dependence of κxy / Tsuggested [5].

References[1] G. M. Luke et al., Nature 394, 558 (1998).
[2] E. R. Schemm et al., Phys. Rev. B 91, 140506 (2015).
[3] N. Yoshioka, Y. Imai, and M. Sigrist, J. Phys. Soc. Jpn. 87, 124602 (2018).
[4] S.-L. Yu and J.-X. Li, Phys. Rev. B 85, 144402 (2012).
[5] X. Wu et al., Phys. Rev. Lett. 127, 177001 (2021).

Title: Development of low temperature relaxation-method
calorimetry for small samples
Fang. Lyu1*, Akito. Sakai1, Takachika. Isomae1, Shunichiro. Kurosawa1, Ryota.
Uesugi1 and Satoru. Nakatsuji1,2,3,4*Presenter
1
Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
2
Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
3
Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins
University, Baltimore, MD 21218, U.S.A
4
Trans-scale Quantum Science Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0033,
Japan
Abstract (up to 200 words)
In solid state physics, specific heat is one of the most fundamental thermodynamic quantities,
reflecting the electronic, spin and lattice degree of freedom. Especially, specific heat at ultralow temperature is especially important for the study of quantum many-body effect andquantum magnetism. In order to measure the specific heat for small samples (< 1 mg)
accurately at ultra-low temperature, it is necessary to reduce the addenda heat capacity
coming from the sample stage (1-3). In this presentation, we report the development of a new
specific heat cell that allows us to measure the heat capacity by the relaxation method down to
T ~ 20 mK. We could reduce the addenda heat capacity by adjusting the thermometer, heater,
and thermal link etc.
References
1.
2.
3.

T. Nomoto et al., Simultaneous measurement of specific heat and thermal conductivity
in pulsed magnetic fields. Rev Sci Instrum 94, (2023).
Y. Matsumoto, S. Nakatsuji, Relaxation calorimetry at very low temperatures for
systems with internal relaxation. Rev Sci Instrum 89, 033908 (2018).
A. Reifenberger, A. Reiser, S. Kempf, A. Fleischmann, C. Enss, Development of anovel calorimetry setup based on metallic paramagnetic temperature sensors. Rev Sci
Instrum 91, 035118 (2020).

Title: NbReSi: a noncentrosymmetric superconductor with large
upper critical field and nodeless superconductivity
H. Su1,2*, T. Shang3, F. Du1, D. Tay4, C. Cao1, T. Shiroka4,5, M. Smidman1, H. Q.
Yuan1
1

Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou
310058, China
2
Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
3
Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic
Science, East China Normal University, Shanghai 200241, China
4
Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Switzerland
5
Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI,
Switzerland

We report the discovery of superconductivity in noncentrosymmetric NbReSi, which
crystallizes in a hexagonal ZrNiAl-type crystal structure with space group P-62m. Bulk
superconductivity, with Tc = 6.5 K was characterized via electrical-resistivity, magnetization,and heat-capacity measurements. A large upper critical field of μ0Hc2(0)~12.6 T is obtained,
which is comparable to the weak-coupling Pauli limit. The low-temperature electronic
specific heat, superfluid density ρsc(T) (determined via transverse-field muon-spin rotation
and relaxation (μSR)) and the spin-lattice relaxation rate T1−1(T) (determined via nuclear
magnetic resonance (NMR)) suggest a nodeless superconductivity with signatures of multigap
in NbReSi. The absence of spontaneous magnetic fields below Tc, as evidenced from zerofield μSR measurements, indicates a preserved time-reversal symmetry in the
superconducting state of NbReSi. The electronic band-structure calculations show that thedensity of states at the Fermi level are dominated by Re and Nb d orbitals, with a sizable band
splitting induced by the antisymmetric spin-orbit coupling. The unusually large upper criticalfield of NbReSi possibly arises from its anisotropic crystal structure.
NbReSi represents a new candidate material for revealing the puzzle of time-reversal
symmetry breaking observed in some Re-based superconductors and its relation to the lack of
inversion symmetry.

References[1] H. Su, T. Shang, F. Du, C. F. Chen, H. Q. Ye, X. Lu, C. Cao, M. Smidman, and H. Q.
Yuan, NbReSi: A noncentrosymetric superconductor with large upper critical field, Phys. Rev.
Materials 5, 114802(2021)[2] T. Shang, D. Tay, H. Su, H. Q. Yuan, and T. Shiroka, Evidence of fully gappedsuperconductivity in NbReSi: A combined μSR and NMR study, Phys. Rev. B 105,
144506(2022)

Development of a circular polarized microwave cavity andmicrowave Hall effect measurements*Masaki Roppongi1, Tomonori Arakawa2, Yuto Yoshino1, Yuto Kinoshita3,
Masashi Tokunaga3, Kenichiro Hashimoto1 and Takasada Shibauchi1*Presenter
1

University of Tokyo,
National Institute of Advanced Industrial Science and Technology,
3
The Institute for Solid-State Physics, University of Tokyo.
2

A microwave cavity has been used for electron spin/ferromagnetic resonance and surface
impedance measurements in condensed matter physics [1]. More recently, it has also been apowerful tool in qubit control and the study of cavity quantum electrodynamics (cavity QED)
[2].
In this study, we have developed a high-Q microwave dielectric cavity, which can generateand control circularly polarized eigenmodes by equipping a hybrid coupler (Fig. 1). It canmaintain a high-Q value (Q ~ 1 × 105) even in a high magnetic field, and the circulardichroism allows us to evaluate the conductivity susceptibility and impedance tensor,
including the off-diagonal term. In this poster presentation, we will present the results of Hall
effect measurements on Bi single crystals in the microwave region obtained from surface
impedance tensors by using the developed circularly polarized cavity.

Fig.1 Our developed circularly polarized microwave dielectric cavity
References[1] O. Klein, S. Donovan, M. Dressel, and G. Grüner, Int. J. Infrared Millim. Waves 14, 2423
(1993).
[2] A. Blais et al., Rev. Mod. Phys. 93, 025005 (2021).

Analogue Hawking radiation with reverse Doppler shift in
Josephson metamaterial transmission lines
Haruna Katayama1,2 and Noriyuki Hatakenaka1*
1
2

Hiroshima University, Japan.
Dartmouth College, U.S.A.

Abstract
We have shown that solitons exist in Josephson metamaterial nonlinear transmission lines dueto their nonlinearity and dispersion, and that these solitons behave analogue black holes. We
have also reported that analogue Hawking radiation occurs there due to quantum-mechanicaleffects [1]. Since the black-hole soliton travels along the transmission line, it is necessary toconsider the Doppler effect when observing the Hawking radiation emitted from the soliton. In
our system, which is a metamaterial transmission line with a negative reflection index, the phasevelocity and group velocity travel in opposite directions, so unlike the conventional Doppler
effect, there is a reverse Doppler effect [2] in which the frequency increases as the sound source
moves away. We will discuss the Hawking temperature considering the reverse Doppler effect.
References[1] H. Katayama et al., Phys. Rev. Res. 5, L022055 (2023).
[2] I. Frank, J. Phys. USSR 7, 49 (1943).

Title: Defect density effect on scattering times in a γ-Al2O3/SrTiO3
2DEG
J. Yang1* and M. Lippmaa1*Presenter
1
ISSP, Univ. of Tokyo, Japan
Abstract (up to 200 words)
The γ-Al2O3/SrTiO3 heterostructure interface is known to form a high-mobility twodimensional electron gas (2DEG) at low-temperatures due to the presence of oxygen vacancies
confined to the interface. Although the origin of the high-mobility and the influence of the γAl2O3 film growth conditions have been studied, the effect of cation defects at the interface,caused by the high kinetic energy of the atoms in the pulsed laser deposition (PLD) plume, on
the transport characteristics has not been explored. The elastic, inelastic, and spin-orbit
scattering lifetimes of carriers forming a 2DEG at the LaAlO3/SrTiO3 interface have been
extracted with the Maekawa-Fukuyama (MF) model.[1]In this work, the scattering lifetimes of carriers of the γ-Al2O3/SrTiO3 2DEG grown at various
ablation plume kinetic energies were extracted by MF fitting of the magnetoconductance data.
Fig. 1 shows the normalized magnetoconductance and MF fitting of the heterostructures in the
0 to 9T magnetic field range. It was possible to fit both low- and high-field regions by addinga Kohler component for the orbital magnetoresistance contribution. The effect of the laser
fluence on the scattering lifetimes of these heterostructures will be presented.

Fig. 1 Magnetoconductance fitting with the MF model for γ-Al2O3/SrTiO3
heterostructures grown at various laser fluences.

[1] G. Herranz et al., Nature Commun. 6, 6028 (2015).

Anisotropic thermal expansion phenomena in Ca2RuO4 type systems

Hena Das1,2 and Masaki Azuma1,2
das.h.aa@m.titech.ac.jp
1

2

Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta,
Midori-ku, Yokohama, Kanagawa 226-8503, Japan

Kanagawa Institute of Industrial Science and Technology (KISTEC), 705-1 Shimoimaizumi,
Ebina 243-0435, Japan

Thermal strains in functional materials can seriously impede their device applications. It is thus,
a technological imperative to minimize the thermal expansion of materials. Negative thermal
expansion (NTE), a rare and interesting phenomenon observed in certain materials which
contract upon heating, can be effectively harnessed to this end. Layered ruthenate Ca2RuO4 is
one such material endowed with this characteristic. A giant NTE within a 200 K temperature
window with a value of 𝛼! ~ − 115 × 10"# /K of the linear coefficient of thermal expansion
was reported in this system recently1, and the phenomenon was attributed to the observed
anisotropic thermal expansion of the system1,2. Ca2RuO4, which crystallizes in a layered
distorted K2NiF4 structure2,3 undergoes multiple phase transition as a function of temperature
with the metal-insulator transition below 357 K4,5. Formation of Ru 4d orbital ordered andantiferromagnetic ordered states were observed below 260 K and 110 K6,7, respectively. In mypresentation, I will elaborate upon the couplings between various order parameters and theirimpact on the thermal expansion properties of this system. Additionally, I will discuss our
findings of high-throughput search for new NTE materials within layered K2NiF4 latticeframework.
[1] K. Takenaka et al., Nat. Commun. 8, 14102 (2017).
[2] L. Hu et al., Chem. Mater. 33 (19), 7665-7674 (2021).
[3] T. F. Qi et al., Phys. Rev. Lett. 105, 177203 (2010).
[4] C. S. Alexander et al., Phys. Rev. B 60, R8422(R) (1999).
[5] E. Gorelov et al., Phys. Rev. Lett. 104, 226401 (2010).
[6] S. Nakatsuji et al., J. Phys. Soc. Jpn. 66, 1868 (1997).
[7] I. Zegkinoglou et al., Phys. Rev. Lett. 95, 136401 (2005).
Acknowledgment: This work is financially supported by JSTCREST (JPMJCR22O1) and the
Kanagawa Institute of Industrial Science and Technology (KISTEC).

Title: Polarized Raman study of antiferromagnet FePS3
Gakuto Kusuno1* and Takuya Satoh1, 2*Presenter
1
Department of Physics, Tokyo Institute of Technology, Japan
2
Quantum Research Center for Chirality, Institute for Molecular Science, Japan
Abstract (up to 200 words)
Layered materials, characterized by van der Waals interaction as the interlayer coupling,exhibit versatile properties suitable for future device applications. FePS3 is a compound ofparticular interest by its layered structure and antiferromagnetism. Below the Néel
temperature, its spins align in a zigzag pattern. Raman spectroscopy, a widely used
nondestructive method, allows for the study of vibrational and magnetic properties ofmaterials. We conducted Raman spectroscopy on FePS3 by using linear polarized light toinvestigate its properties. The polarization azimuth angle dependence of scattering intensity
undergoes a significant change near the Néel temperature. Additionally, we found that theazimuth angle dependence below the Néel temperature can be explained by introducing aphase difference to the diagonal elements on the Raman tensor. This anisotropic nature isconsistent with other low-symmetry layered materials, such as black phosphorus [1] ortransition metal dichalcogenides [2]. These findings demonstrate that magnetic ordering
induces in-plane anisotropy in the scattering intensity of FePS3.
References[1] J. Kim et al., Nanoscale 7, 18708 (2015).
[2] Q. Song et al., Sci. Rep. 6, 29254 (2016).

Thermal Hall effect in the antiferromagnetic Skyrmion lattice
H. Takeda1*, M. Kawano2, K. Tamura1, M. Akazawa1, J. Yan1, T. Waki3, H.
Nakamura3, K. Sato4, Y. Narumi4, M. Hagiwara4, M. Yamashita1, and C. Hotta5
1

Institute for Solid State Physics, Univ. of Tokyo, Japan
Dept. of Physics, Tech. Univ. of Munich, Germany
3
Dept. of Materials Science and Engineering, Kyoto Univ., Japan
4
Center for Advanced High Magnetic Field Science, Osaka Univ., Japan
5
Dept. of Basic Science, Univ. of Tokyo, Japan
2

Abstract
Magnon, a fundamental quasi-particle in magnetic materials, has attracted great attentions due
to its intriguing heat and/or spin transport phenomena. One of the prominent phenomena is
the thermal Hall effect. The magnon experiences the emergent gauge field originating fromthe nontrivial spin texture or antisymmetric exchange interaction, which results in theappearance of the transverse thermal conductivity. Indeed, the magnetic insulator GaV4Se8
which hosts a ferromagnetic Skyrmion lattice exhibits the magnon thermal Hall effect due tothe U(1) gauge field generated by the magnetic vortices[1, 2]. In this presentation, we focus
on the thermal transport properties on a new class of Skyrmion lattice, the antiferromagnetic(AFM) Skyrmion lattice composed of three sets of the ferromagnetic Skyrmion lattices[3].
We show the experimental observation of the thermal Hall effect in the three sub-lattice AFM
SkL state realized in MnSc2S4[4]. The spin wave theory calculation show that the heat
carriers can be described by the magnon in SU(3) gauge field originating from the three sublattice structure.
References[1] Y. Fujima et al., Phys. Rev. B 95, 180410(R) (2017).
[2] M. Akazawa et al., Phys. Rev. Research 4, 043085 (2022).
[3] S. Gao, et al., Nature 586, 37 (2020).
[4] H. Takeda et al., arxiv:2304.08029.

Title: Magnetic resonance frequencies in a two-sublatticeferrimagnet with a magnetic compensation point
Kouki Mikuni1*, Toshiki Hiraoka1, Takumi Kuramoto2, Yasuhiro Fujii2,
Akitoshi Koreeda2, and Takuya Satoh1, 3*Presenter
1
Department of Physics, Tokyo Institute of Technology, Japan2
Department of Physical Sciences, Ritsumeikan University, Japan
3
Quantum Research Center for Chirality, Institute for Molecular Science, Japan
Abstract (up to 200 words)
Ferrimagnetic materials are the materials that possess ferromagnetic or antiferromagnetic
properties depending on the temperature, providing a rich platform for both physics andapplications. However, the understanding of the dynamics of ferrimagnetic materials is still not
fully developed due to the complexities at the magnetic compensation temperature where thenet magnetization disappears. In order to overcome it, we obtained the resonance frequencies
by analytically solving the Landau-Lifshitz-Gilbert equation for bismuth-substituted rare-earth
iron garnet, a two-sublattice ferrimagnetic material. As the result, our solution is applicable
across all temperature ranges, including the magnetic compensation temperature. Our
calculation results are consistent with experimental findings obtained by Brillouin lightscattering and pump-probe measurements, taking into account the exchange stiffness and thetemperature dependence of magnetic anisotropy in the free energy. With this result, it is possible
to enhance the understanding of magnetic dynamics of ferrimagnetic materials. Furthermore,
the same approach can be applied for other ferrimagnetic materials with uniaxial anisotropy.
Future prospects include the creation of new magnetooptical devices that utilize the fastmagnetic response of ferrimagnetic materials over all temperature ranges.

Large Hall Signal due to electrical Switching at Mn3Sn/heavy
metal multilayers
A

Dept. of Phys. ,B

ISSP Univ. of Tokyo, CCREST,DCEMS RIKEN

H. TsaiA,C, T. HigoA,C, K. KondouC,D, S. SakamotoB, A. KobayashiB, T. MatsuoA, S. MiwaB,C,
Y. OtaniB,C,D & S. NakatsujiA, B, C

The electrical manipulation of a topological state is crucial for utilizing the robust properties of
topological materials in electronic devices. Recently, such manipulation is realized in theantiferromagnetic Weyl semimetal Mn3Sn[1,2] through the readout signal of anomalous Hall effect in
the Mn3Sn/heavy metal (Pt, W) heterostructures[3]. Here, we reported that the switching of Hall signalof Mn3Sn/heavy metal multilayer can be significantly enhanced by: (i)adjusting the crystal orientationof Mn3Sn by removing Ru buffer layer, and (ii) changing the interfacial condition by annealing at theinterface between Mn3Sn and the heavy metal. Compared to the reported switching Hall signal in
Ru/Mn3Sn/Pt multilayers, the switching Hall resistance becomes one order larger, ~0.35 Ω, in the
Mn3Sn/W devices. The readout voltage can be increased to mV order by increasing the read current.
Moreover, by investigating the thickness dependence of Mn3Sn layer, we found that the effective
switching thickness in Mn3Sn layer could go up to 40nm, which is much thicker than ferromagnetic
materials. Furthermore, we investigate the initial state dependence of the Mn3Sn switching, and also
the influence of the adding insertion layer Cu between Mn3Sn heavy metal layer.
[1] S. Nakatsuji, N. Kiyohara, T. Higo, Nature 527, 212-215 (2015).
[2] T. Higo, et al. APL 113, 202402 (2018).
[3] H. Tsai, T. Higo, et al. Nature 580, 608–613 (2020).

Title: Extremely Large Magnetoresistance and Anisotropic Transport
in Multipolar Kondo System PrTi2Al20○Takachika Isomae1, Akito Sakai2, Mingxuan Fu1,2 Takanori Taniguchi3, Masashi
Takigawa1,4,5, and Satoru Nakatsuji1,2,6,7,8
1
ISSP, 2Univ. of Tokyo, Dept. of Phys., 3IMR, Tohoku Univ., 4KEK-IMSS, 5Toyota Riken,
6
CREST, 7JHU, 8Trans-scale Quantum Science Institute, Univ. of Tokyo,
Quadrupolar Kondo lattice (QKL) system PrTi2Al20 serves as a suitable platform for
exploring exotic transport phenomena induced by multipole moments [1,2]. The investigationof the system's transport properties under magnetic fields involved the measurement oftransverse magnetoresistance and Hall effect in both PrTi2Al20 and its non-4f analog,
LaTi2Al20. At elevated temperatures, the transport behaviors of PrTi2Al20 notably diverge
from those of LaTi2Al20, potentially due to quadrupole-induced scattering. Conversely, atlower temperatures, both systems exhibit comparable characteristics, displaying unsaturated
and significantly large quasi-linear magnetoresistance attributed to the open orbits mechanism[3].
References[1] A. Sakai and S. Nakatsuji, J. Phys. Soc. Jpn. 80, 063701 (2011).
[2] T. Onimaru and H. Kusunose, J. Phys. Soc. Jpn. 85, 082002 (2016).
[3] T. Isomae et al., Phys. Rev. Research 6, 013009 (2024).

Composition variation behavior of galvanomagnetic effect in
GdFe collinear coupled ferrimagnetic alloy thin films
Yuki Kobayashi1*, Yoshihiro Sou1, Yuichi Kasatani2, Hiroki Yoshikawa2, andArata Tsukamoto2*Presenter
1
Graduate School of Science and Technology, Nihon University, Japan.
2
College of Science and Technology, Nihon University, Japan.
Abstract (up to 200 words)
We focus on the electron transport phenomena in ferrimagnetic alloys with collinear
antiferromagnetic spin subnetworks. These phenomena are expected to be used to electricallydetect magnetic information via the anomalous Hall effect (AHE) and to harvest energy fromthe environment via the anomalous Nernst effect (ANE)[1]. In this study, we investigated GdFe
alloy thin films. The longitudinal resistance ρxx and the lateral resistance ρxy were measured forvarious composition ratios of Gd and Fe. Then the AHE and ANE were evaluated. The AHE
and ANE increased significantly with the addition of Gd to pure Fe, and showed non-linear
variation with Gd composition, which has a local maximum[2]. Furthermore, in the ρxx-ρxy
correlation, ρxy showed a larger ρxx dependence than that of typical ferromagnetic materials[3][4].
Additionally, we investigated the contribution of the AHE to the anomalous Nernst coefficientby measuring the Seebeck effect (SE) in this material.

References[1] M. Mizuguchi and S. Nakatsuji, Sci. Technol. Adv. Mater. 20, 262-275 (2019).
[2] Y. Kobayashi et al., T. Magn. Soc. Jpn. (Special Issues) 7, 34-39 (2023).
[3] T. Chen et al., Nat. Commun. 12, 572 (2021).
[4] T. Miyasato et al., Phys. Rev. Lett. 99, 086602 (2007).

Anisotropic transport properties in transition metal dichalcogenide TiSe2
A

Dept. of Phys. Univ. of Tokyo, BISSP Univ. of Tokyo, CTrans-scale Quantum Science Institute
Y. KajiwaraA, Z. FengA,B, S. MinamiA,
S. AkamatsuA, D. HamaneB, A. SakaiA and S. NakatsujiA,B,C

Transition metal dichalcogenides are materials in which two group 16 chalcogenelements are arranged in an octahedral or triangular prismatic configuration around asingle transition metal element, often in a layered crystal structure[1]. Among them,
TiS2 is expected to exhibit various anisotropic transport properties because of its twodimensional structure, in which Ti and S are arranged in an octahedron and Ti and S
layers are stacked by van der Waals forces[2]. In addition, topological states have been
observed in Ti compounds with Te and Se as chalcogen elements in TiTe2 under highpressure [4] and superconductivity in TiSe2 [5], and such phenomena are expected tooccur in TiSe2-xTex as well[6].
Research has also been conducted on polycrystalline samples of TiS2 sintered by spark
plasma sintering (SPS)[3], a technique in which an electric current is applied underpressure and thermal and plasma energies are applied to sinter the sample. Anisotropictransport properties can be controlled by changing the composition ratio of Ti and S,
taking advantage of the easy penetration of atoms into the van der Waals gap between
layers[3]. In this study, polycrystalline samples of TixS2 and TiSe2-xTex with various
composition ratios were synthesized by a two-step heat treatment involving solid phasereaction and SPS. The orientation and composition ratios were investigated by X-ray
diffraction and SEM-EDX, and anisotropic transport properties were measured at low
temperatures. The band gap was controlled by changing the composition ratio of TiSe2xTex, and physical phenomena near the metal-insulator transition were investigated.
In this talk, we will discuss the results obtained from first-principles calculations andthe transport properties and orientation in the SPS-supported polycrystalline samples
TixS2 and TiSe2-xTex.
[1] J. A. Wilson and A. D. Yoffe, Adv. Phys., 18, 193 (1969).
[2] Nina Glebko and Antti J. Karttunen, Phys. Rev. B. 100, 024301 (2019).
[3] M. Beaumale et al., Acta. Mater. 78, 86 (2014).
[4] Zhang, Min, et al., Appl. Phys. Lett. 112, 041907 (2018).
[5] Joe, Y., Chen, X., Ghaemi, P. et al., Nature Physics 10.421–425 (2014).
[6] Zhiyong Zhu, et al., Phys. Rev. Lett. 110, 077202 (2013).

Title: Quantum Phases of Helium Three on Graphite Plated with
Bilayer of HD
T. Kaji1, S. Murakawa1
1

Cryogenic Research Center, University of Tokyo

Abstract (up to 200 words)
Helium three (3He) is an atom with nuclear spin 1/2. The atom is absorbed on graphite
and regulated on two dimensions at low temperature. Therefore, 3He on graphite (3He/gr)
enables us to research two-dimensional magnetism.
3He/gr undergoes structural phase transition when changing its areal density and shows
various phases. From lower areal density, the system mainly has self-condensing phase, Fermi
liquid phase, commensurate phase and incommensurate phase. Bare graphite is often platedwith 3He, 4He, and hydrogen in order to corrugate the first layer of 3He.
For graphite plated with a bilayer of hydrogen, two phases with specific heat capacity
were found [1]. Although those ground states are suggested to be quantum crystal liquid andquantum spin liquid, these microscopic structures have not been cleared [1]. In particular, oneof the two ground states is considered to be an elementary excitation of Majorana Fermion [1].
Thus, the purpose of our research is to clarify the microscopic structures of the groundstates of the two phases. The method is measuring spin-spin relaxation time and magnetic
susceptibility with NMR.
Currently we prepare the NRM cell and the NMR system for the measurement.
References[1] M. Kamata, Ph.D. Theses, University of Tokyo (2018)

Large Spin-Orbit Coupling Systems for Emerging Physics andSpintronics Applications
Xufeng Kou
School of Information Science and Technology, ShanghaiTech University
Abstract: Spintronics, which uses spin as the building block for information process,has become an emerging area in the Post-Moore ear. In order to address current
challenges of spintronics, opportunities may exist for a focus research on theunderstanding and manipulation of fundamental spin-orbit coupling (SOC) in solidstate materials. In this talk, I will present our work on the control of spin/magnetic statesin magnetic topological insulators and narrow bandgap semiconductor-based
heterostructures. The independent manipulation of the topology of energy band and themagnetic exchange order enables us to construct non-reciprocal devices and novel
artificial neural network computing paradigm. In addition, I will also summarize ourwork on utilizing interfacial Rashba SOC in lattice-matched InSb/CdTeheterostructures for realizing gate-tunable non-reciprocal charge transport and spinorbit-torque-based magnetization switching with highly spin-to-charge conversion
efficiency at room temperature. Our work may help construct a wide range of ultralowpower spin−orbitronics applications.
Biography: Dr. Xufeng Kou received his BS degree (with honor) in Chu Kochen
Honors College from Zhejiang University (2009). From 2009 to 2015, he received his
MS and PhD degrees in Electrical Engineering from UCLA. Since February 2016, hejoined the School of Information Science and Technology at ShanghaiTech University.
So far, Dr. Kou has published 3 book chapters, and co-authored more than 90 peerreviewed journal/conference papers including Nature Electronics, Nature Materials,
Nature Nanotechnology, Nature Communications, Physical Review Letters, and IEEE
IEDM. with more than 7000 citations (h-index of 36). He also holds several awards
including the Qualcomm Innovation Fellowship (2012), Chinese Outstanding Student
Abroad Scholarship (2013), Distinguished PhD Dissertation Award of UCLA (2015),
Shanghai May 4th Youth Medal (2018), Shanghai 35U35 Award (2021), and Shanghai
Pudong Elite Researcher Award (2023).