Abstract Book
4th Emallia Conference
Hokkaido Univ.-Pusan Univ.-RIKEN Symposium

Hokkaido University,
23th-25th of July, 2018
(1) Oral Presentations(2) Poster Presentations

(1) Oral Presentations
23th of July
@Academic rounge 1 & 2 in the faculty of engineering (9:40-18:45)
24th of July
@Academic rounge 1 & 2 in the faculty of engineering (9:00-18:00)
25th of July
@2-211 in the faculty of science (9:30-15:00)

23th, session 1, Invited speaker 1

High-Tc mechanism of iron-based superconductors
Hiroyuki Yamase1,2 and Tomoaki Agatsuma1,2
12National Institute for Materials Science, Tsukuba, Japan
Graduate School of Science, Hokkaido University, Sapporo, Japan

Iron-based superconductors were discovered as a new family of high-Tc superconductivity[1]. Typically the superconducting phase is realized close to the spin-density-wave phase andspin fluctuations are believed to be an important source to drive superconductivity. A close
look at the phase diagram reveals that the superconducting phase is closer to the so-called
electronic nematic phase where the fourfold symmetry is broken spontaneously by electronic
correlations. Hence fluctuations associated with the nematic phase are also expected to play
an important role for superconductivity.
In this talk, we consider nematic fluctuations originating from the occupation diﬀerence ofdxz and dyz orbitals, namely orbital nematic fluctuations and show that the orbital nematicfluctuations can be a new high-Tc mechanism of iron-based superconductors. We study aminimal two-band model consisting of dxz and dyz orbitals, where electrons interact witheach other via orbital nematic and spin-exchange interactions. We then compute the onset
temperature of superconductivity as well as the momentum dependence of the paring gap byincluding the electronic self-energy eﬀect in the framework of the Eliashberg theory. Technically there are two successes: inclusion of the self-energy eﬀect and computation at low
temperature which allows us to evaluate Tc of superconductivity. We find that (i) orbital
nematic fluctuations can drive superconductivity with Tc comparable with experimental data
[2, 3], (ii) spin fluctuations, on the other hand, are less eﬀective for the superconducting
instability, although they can drive superconductivity [4], and (iii) orbital nematic and spin
fluctuations work competitively for the superconducting instability and high-Tc is achieved
when orbital nematic fluctuations are dominant [4].
[1] Y. Kamihara, T. Watanabe, M. Hirano, and H. Hosono, J. Am. Chem. Soc. 130, 3296 (2008).
[2] H. Yamase and R. Zeyher, Phys. Rev. B 88, 180502(R) (2013).
[3] T. Agatsuma and H. Yamase, Phys. Rev. B 94, 214505 (2016).
[4] T. Agatsuma, Ph. D. thesis, Hokkaido University.

1

23th, session 1, speaker 1
2018. 07. Emillia conference (due on 9 July)

Investigation the origin of charge carrier in NiO by Na doping
Seojin Yang1, Jiwoong Kim1, Jong-Seong Bae2, Sungkyun Park1,*
1

Department of Physics, Pusan National University, Busan 46241, Korea
2

Busan Center, Korea Basic Science Institute, Busan 46742, Korea

Transparent conductive materials have been consistently attracted due to demand of advanced
transparent electrodes. NiO which has large band-gap of 3.6 ~ 4.0 eV, chemical stability and p-typecharacteristic is one of the good candidates as advanced transparent electrode materials. However, due
to the lack of hole concentration, it is not easy to be used in current application. Therefore, improving
hole carrier concentration, understanding the source of the conducting charge, and mechanism areimportant subjects of recent research field. In this study, we demonstrated the possible controllingelectrical properties by Na-doping on NiO powders. Electrical resistivity of Na-doped NiO was
increased with increasing Na doping (until 9%) even though it possesses n-type characteristics, except
for the sample under 1% doping. Interestingly, the portion of oxygen vacancy was enhanced with Nacontents examined by X-ray photoelectron spectroscopy. This suggest that oxygen vacancy is able toact as donor in NiO system.
This study was supported in part by NRF Korea (NRF-2017K1A3A7A09016305 and NRF2018R1D1A1B07045663).

*

E-mail: psk@pusan.ac.kr

23th, session 1, speaker 2

ESR study of the triangular lattice system X[Pd(dmit) 2]2
Sunghyun Kim1, 2，Yugo Oshima1, 2，Reizo Kato2
Hokkaido Univ.1, RIKEN2

The magnetic ground state of S=1/2 antiferromagnetic triangular lattice
has been debated for many decades in condensed matter physics since the groundstate is highly degenerated due to the geometrical frustration of the spins, and theanion radical salt X[Pd(dmit)2]2 (X is a monovalent cation) is one of the materials
which consists of S=1/2 antiferromagnetic triangular lattice. A wide variety ofground states, such as quantum spin-liquid (QSL) state, antiferromagnetic longrange ordered (AFLO) state, charge-ordered (CO) state have been observed
depending on the degree of geometrical frustration (frustration parameter t’/t)controlled by the monovalent cation X (Fig. 1). Especially, EtMe3Sb[Pd(dmit)2]2
does not exhibit long-range order down to 30 mK, and spin-liquid like behavior
is observed in the heat capacity and NMR measurements [1]. However, the natureof the QSL state, whether the excited state is gapless or gapped, is not clarified
yet. For example, heat capacity, thermal conductivity suggest a gapless excitation,
whereas NMR measurement suggests a gapped excited state.
We have previously reported that unconventional behaviors of the ESR
linewidth are observed by ESR measurement [2]. We propose that the ESR is
directly observing the spinon, which is the elementary excitation of QSL state,
and the peculiar ESR linewidth behavior reflects the dynamics of the spinon.
However, it is still not clear how muchspin is contributing to the spin
excitation. Therefore, we have verified
the spin density of the X[Pd(dmit)2]2system by using the spin counting
method of ESR. In the presentation, we
present our results of the spin counting
for several X[Pd(dmit)2]2 salts, and its
ground state is discussed.

Reference[1] R. Kato, Bull. Chem. Soc. Jpn., 87 (2014)355-374.
[2] 大島勇吾 他, 日本物理学会, 第 70 回年次大会, 24pAB-11

Fig. 1

Phase diagram of X[Pd(dmit)2]2 [1]23th, session 1, speaker 3

Nonreciprocal magnon excitations on a breathing kagome lattice1
1

T. Matsumoto, 1 S. Hayami

Dept.of Phys., Hokkaido Univ .

In condensed matter physics, the breakings of time-reversal and spatial inversion symmetries give rise to fascinating phenomena, such as magneto-optical and magneto-electric eﬀects.
Among them, nonreciprocal phenomena, which shows a rectification, have been much interest,since they induce unconventional transport properties and excitations. From a microscopic pointof view, nonreciprocal phenomena in metallic systems occur once the wave numbers of electrons
k and −k are inequivalent in the absence of both time-reversal and spatial inversion symmetries.

Meanwhile, besides metals, similar nonreciprocal physics also occurs even in noncentrosymmetric magnetic insulators. There, magnon excitations show a rectification, which originates fromthe interplay between the Dzyaloshinskii-Moriya (DM) and exchange interactions [1–4]. Recently, such nonreciprocal magnon excitations were observed in a noncentrosymmetric ferromagnet LiFe5 O8 through microwave absorption spectra [1] and α-Cu2 V2 O7 by inelastic neutron
scattering experiment [2]. Moreover, interesting possibilities of further nonreciprocal physics,
such as the nonreciprocal optical eﬀect [5, 6] and nonreciprocal spin Seebeck eﬀect [3, 4], havebeen extensively studied. However, the conditions to obtain nonreciprocal magnon excitations
have not been fully understood. It is desirable to clarify fundamental ingredients to obtain suchnonreciprocal magnon excitations.
Motivated by these studies, we investigate when and how nonreciprocal magnon excitations
are realized in magnetic insulators. We here consider a breathing kagome system in the absenceof spatial inversion symmetry. First, we construct a spin model with symmetric anisotropic exchange and antisymmetric DM interactions in addition to the isotropic one from the symmetry
point of view. Next, we calculate the ground-state phase diagram of the model in a wide rangeof model parameters. By examining magnon excitations for each magnetic ordering within the
Holstein-Primakoﬀ approximation, we clarify the conditions to obtain nonreciprocal magnon excitations from the symmetry point of view. Furthermore, we find the toroidal moments degree of
freedom, which are often accompanied with magnetic orderings in noncentrosymmetric crystals,
play an essential role in realizing nonreciprocity. In the presentation, we discuss what types ofnonreciprocal magnon excitations are realized in various type of magnetic orderings and clarify
a role of toroidal moments microscopically.
[1] Y. Iguchi, S. Uemura, K. Ueno, and Y. Onose, Phys. Rev. B 92, 184419 (2015).
[2] G. Gitgeatpong et al., Phys. Rev. Lett. 119, 047201 (2017).
[3] R. Takashima, Y. Shiomi, and Y. Motome, Phys. Rev. B 98, 020401(R) (2018).
[4] Y. Shiomi et al, Phys. Rev. B 96, 180414(R) (2017)[5] Y. Takahashi et al, Nature Physics 8, 121 (2012)[6] S. Miyahara and N. Furukawa, J. Phys. Soc. Jpn. 81, 023712 (2012); Phys. Rev. B 89, 195145(2014).

1

23th, session 1, speaker 4

Combined DFT and STM studies of SnSe and SnSe1-xSx alloys
Taewon Min1, Ganbat Duvjir2, Trinh Thi Ly2, Jinho Byun1, Taehoon Kim2, Mahmoud M. Saad2,
Nguyen Thi Minh Hai2, Anh-Tuan Duong2, Sunglae Cho2, S.H. Rhim2, Jungdae Kim2, Jaekwang
Lee*1
1

Pusan National University, Department of Physics, Busan 46241, South Korea

2

Ulsan University, Department of Physics, Ulsan 44610, South Korea
E-mail: jaekwangl@pusan.ac.kr

SnSe single crystal has been found to exhibit excellent thermoelectric performance with anextremely high ZT (figure of merit) value of 2.6. Although this high ZT value has attracted
considerable attention, the origin of p-type character of SnSe has yet to be clearly understood.
Here, by combining scanning tunneling microscopy (STM) and density functional theory (DFT)
calculations, we find that the most dominant Sn vacancies generate the defect state inside thedispersive valence band and produce extra holes throughout the entire system. On the other hand,
other intrinsic vacancies create a nondispersive donor level and generate immobile electrons
localized near the vacancy site. Our combined STM/DFT studies can provide important
information for the development of highly efficient SnSe-based thermoelectric devices. In addition,
we will show the structural evolution of SnSe1-xSx alloys at the atomic level.
This work was supported by the National Research Foundation of Korea (NRF) grant funded by
the Korea government (2018R1A2B6004394). Also this work was supported by the National
Research Foundation of Korea (NRF) Grant funded by the Korean government (MSIP) (NRF2015R1C1A1A01053810).

23th, session 2, invited speaker 2First-principles studies of complex oxides interfaces
Taewon Min, Jinho Byun and Jaekwang Lee*1

Department of Physics, Pusan National University, Busan 46241, South Korea
Corresponding author. E-mail: Jaekwangl@pusan.ac.kr

Abstract
The Oxide interfaces have attracted considerable attention in recent years due to emerging
novel properties that do not exist in the corresponding parent compounds. Furthermore, modern
atomic-scale growth and probe techniques enable the formation and study of new artificial
interface states distinct from the bulk state. A central issue in understanding the novel
phenomena in oxide heterostructures is to reveal how various physical variables (spin, charge,
lattice and/or orbital hybridization) interact with each other. Here, using density functional
theory calculations, we explore the electronic, magnetic and structural properties developed
near the complex oxide interfaces such as SrTiO3/LaAlO3 and Fe/PbTiO3. We study theinterplay between physical interactions, and quantify parameters that determine physicalproperties of heterostructures. Our theoretical studies help understanding how physicalvariables couple with each other and how they determine new properties at oxide interfaces.

23th, session 2, speaker 5

Multi-frequency ESR studies ofthe π-d molecular conductor λ-(STF)2FeCl4
Taehoon Lee1,2, Yugo Oshima1,2, Takaaki Minamidate1, Yohei Saito2,
Atsushi Kawamoto2, Noriaki Matsunaga2 and Reizo Kato1
RIKEN1, Hokkaido University2λ-(BETS)2FeCl4 is a π-d molecular conductor with strong π-d interaction. Dueto this π-d interaction, this system has a fascinating phase diagram [1]. We havepreviously investigated λ-(BETS)2FeCl4 using ESR spectroscopy. Typical angulardependence of the g-value has a sinusoidal curve, however, anomalous minima of
the g-value was observed [2]. We think the origin of the minima is due to the π-dinteraction between Se or S in the BETS molecule and FeCl4- anion. For
understanding the π-d interaction effect, we have investigated another π-d system,
which is λ-(STF)2FeCl4. λ-(STF)2FeCl4 is an insulator and becomes a conductor
under pressure, and antiferromagnetic long-range order is observed below TN=16
K [3]. STF is an asymmetric molecule, half side is the same with BETS and theother half has no Se atoms as shown Fig. 1. Hence, similar π-d interaction with λ(BETS)2FeCl4 is expected for the half BETS side, but, the other half has only
contact with S atoms.
In the previous theoretical study, the easy-axis of λ-(BETS)2FeCl4 is tilted 30°
from the c-axis due to the π-d network [4]. The antiferromagnetic resonance of λ(STF)2FeCl4 is observed when the magnetic field is tilted 35° from the c-axis. It
suggests the easy-axis of λ-(STF)2FeCl4 is also tilted from the c-axis. Hence, the πd interaction in λ-(STF)2FeCl4 seems to exist. However, λ-(STF)2FeCl4 has the
typical angular dependence of the g-value in contrast with λ-(BETS)2FeCl4 as
shown Fig. 2. Hence, the π-d interaction of λ-(STF)2FeCl4 might be weaker thanλ-(BETS)2FeCl4.

Fig. 1. Structure of BETS and STF
molecules
Reference
Fig. 2. Angular dependence of[1] Y. Oshima et al., Magnetochemistry, 3(1) (2017) 10
the g-value of λ-(STF)2FeCl4[2] T. H. Lee et al., 72nd Annual JPS meeting, 17aC21-4,
March 17-20 2017[3] T. Minamidate et al., Phys. Rev. B 97 (2018) 104404[4] H. Shimahara et al., J. Phys. Soc. Jpn. 85 (2016) 043708

23th, session 2, speaker 6

Many-Body Eﬀects
in Bose-Einstein Condensates(BECs)
Dept. of P hys., Hokkaido U niv.
A. Kirikoshi

Bose-Einstein condensation is a phase transition phenomenon in which macroscopic number ofparticles form a coherent state at a certain temperature in a multiparticle system. BEC has beenstudied actively in both experimental and theoretical approach.
Bogoliubov theory is a widely known as a theory describing a weakly interacting bosons[1] . According to this theory, an elementary excitation called Bogoliubov mode has a linear dispersion andan infinite lifetime in the long wavelength limit. However, Bogoliubov theory does not incorporate
3/2-body correlation, which is a particle exchange process between condensate and non condensate,and 2-body correlation, which is a process of momentum exchange between non-condensed particles.
Costructing the self-consistent mean-field theory (Hartree-Fock-Bogoliubov (HFB) theory)[2] with the
Bogoliubov mode as a thermal excitation, a finite energy gap appears in the one-particle excitation, which contradicts Hugenholtz-Pines theorem that the one-particle excitation must be a gaplessexcitation[3] .
Recently, a variational wave function for the ground state of weakly interacting bosons incorportating
the dynamical 3/2-body processes was constructed[4] . This wave function gives a lower energy thanthe HFB theory[2] . These processes are also shown (i) to transform the one-particle excitation into
a bubbling mode having the finite lifetime even in the long wavelength limit and (ii) to correct thestability condition for 2-component miscible state[5] .
To investigate the properties of many-body eﬀects, we try to extend the variational approach to finite
temperatures. First, we construct a variational density matrix incorporating 3/2-body correlations,and then evaluate the grand potential using Green’s function. This method makes it possible toinvestigate the temperature dependence of the many-body eﬀects in the BEC phase. We apply thismethod to a low temperatrue system and find that the 3/2-body correlations contribute to lowering
the free energy as in the case of zero temperature system.

[1] N. N. Bogoliubov, J. Phys. (USSR) 11, 23 (1947).
[2] M. Girardeau and R. Arnowitt, Phys. Rev. 113, 755 (1959).
[3] N. M. Hugenholtz and D. S. Pines, Phys. Rev. 116, 489 (1959).
[4] T. Kita, J. Phys. Soc. Jpn. 86, 044003 (2017).
[5] W. Kohno, A. Kirikoshi, and T. Kita, J. Phys. Soc. Jpn. 87, 034002 (2018).

23th, session 2, speaker 7

Standard Model and Grand Unified Theory
Hikaru Uchida
Division of physics, Graduate School of Science, Hokkaido University

The interactions needed to compose atoms are electromagnetic (EM) interaction, weakinteraction, and strong interaction. Natural phenomena can be explained by these threeinteractions other than gravity, and these are induced from the corresponding symmetries. In
particular, EM interaction is induced from U(1)Q local symmetry depending on the EM charge theparticle has. Weak interaction is induced from SU(2)L local symmetry between left handed up
quark and down quark or neutrino and electron. And strong interaction is induced from SU(3)C
local symmetry among three color charges that quarks have. However, since weak bosons, inducing
weak interaction, have their mass, strictly there is no SU(2)L local symmetry. And weak bosons also
have their EM charges. Then weak interaction and EM interaction, at higher energy scale, areoriginally the same interaction called electroweak interaction induced from SU(2)L×U(1)Y local
symmetry. This symmetry is spontaneously broken at about 100GeV so weak interaction is induced
by weak bosons which obtained their mass. On the other hand, EM interaction is induced from
unbroken U(1)Q symmetry. Thus adding SU(3)C local symmetry inducing strong interaction toelectroweak interaction, natural phenomena can be explained by SU(2)L×U(1)Y×SU(3)C local gagesymmetry, which induces EM, weak, and strong interactions, other than gravity. This is thestandard model.
However, there are the following mysteries in the standard model: (i) left-right asymmetry, (ii)strong interaction is independent of the other two interactions and quark-lepton asymmetry, and(iii) Abelian U(1)Y has some disadvantage such as unclear derivation of Y.
There is a model to overcome these mysteries. That model is the model with SU(2)L×SU(2)R×
SU(4)C fundamental local gauge symmetry where fourth color is lepton number at the higher
energy scale than that of the standard model. So this model, called the Patti-Salam Model, is a nonAbelian grand unified model for three interactions, those are EM, weak, and strong interactions
with left-right and quark-lepton symmetry. In this model, there are two steps of spontaneous
symmetry breaking: SU(2)L×SU(2)R×SU(4)C → SU(2)L×U(1)Y×SU(3)C → U(1)Q×SU(3)C.
Besides, I will show another approach to construct this model from string theory.

Reference
J. C. Pati, (2017) arXiv:1706.09531v1 [hep-ph]23th, session 2, speaker 8

The Standard Model from Superstring Theory
Yuki Kariyazono
Division of physics, Hokkaido U niversity
Physics has developed with an idea of unification. Electricity and magnetism wereunited in 19th century, and electromagnetic force and weak force were united in 20th
century. The electroweak theory together with QCD form the Standard Model. Now
we can describe almost all experimental results using the Standard Model and thetheory of relativity. However, there are many problems. For example, the Standard
Model cannot describe quantum gravity. In the processes at short distance, nonrenormalizable ultraviolet divergence appears. Many physicists believe that there isa unified theory of all forces in nature. The superstring theory is a candidate fora unified theory that reconcile the quantum theory and the theory of relativity. In
superstring theory we introduce an extended object called a string with a minimal
length. There are two types of string, an open string and a closed string. When we
pay attention to open strings’ boundary conditions, we can find that endpoints of all
open strings are attached to some physical objects called D-branes. From the statesof string attached to D-branes, we can obtain the same states as in the Standard
Model.

23th, session 2, speaker 9

Contribution to the power spectrum from curvature andradiation during pre-inflation era
Tadashi Sasaki and Hisao Suzuki
Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
Inflation is exponential expansion of the universe which is now believed to have occured in thevery early stage of our universe. This scenario can explain the flat power spectrum of the observed
fluctuations in the cosmic microwave background (CMB), and resolve the flatness and horizon
problem as well.
In this study, we consider the eﬀect of spatial curvature, radiation, and inflaton potential
energy, which are expected to dominate the pre-inflation era, on the power spectrum. Under
the assumption that the energy scale of the inflation is much less than the Planck scale, at whichquantum gravitational eﬀect is no longer negligible, we can treat the spacetime geometry in classicalgeneral relativity, where time evolution of the universe is described by the Friedmann equation.
First, we show that the Friedmann equation can be solved exactly by using the Weierstrass’s elliptic
functions ℘(z). After that we consider a massless scalar field on that spacetime. The equation of
motion turns out to be the Lamé equation and is solved exactly. We take a solution which behaves
like the positive frequency mode in the flat spacetime in the past infinity for large wave number asa mode function for quantization. Assuming that the initial state of the scalar field is the vacuum
state associated with this mode function, we obtain the power spectrum (figure 1). We will briefly
disscuss the possible eﬀect of curvature on the CMB fluctuation.

Figure 1: Power spectrum Pχ (k/H) normalized by (H/2π)2 for (left) negative curvature/(right)
positive curvature.

23th, session 3, speaker 10

First-principles studies of the effects of oxygen vacancies on
the HfO2-based ferroelectric tunnel junction
Jinho Byun1, Taewon Min1, Jaekwang Lee*1
1

Department of Physics, Pusan National University, Busan 46241, Korea
Corresponding author. E-mail: Jaekwangl@pusan.ac.kr

Abstract:
Owing to the recent advances in the oxide growth technology, ferroelectricity has been stabilized evenin a few nm-thick film, which makes it possible to realize the oxides-based ferroelectric tunneling
junction (FTJ) combining the quantum-mechanical tunneling phenomena and switchable spontaneouspolarization into novel device functionality. Among various ferroelectric oxides, HfO2 is the mostpromising material for FTJ devices since it has the great advantage of complementary metal-oxidesemiconductor (CMOS) process compatibility. Despite this considerable attention, the influence ofoxygen vacancies on the tunneling current has not been clearly understood yet. Here, using firstprinciples density functional theory calculations, we explored the role of interfacial oxygen vacancy on
the tunneling current in the TiN/HfO2/metal devices at the atomic scale. We find that the tunnelingcurrent in defective HfO2 is enhanced by over three orders of magnitude compared to plain HfO2 thinfilm. Our results show that the modulation of electronic properties via interfacial oxygen vacancy havea significant impact on HfO2-based FTJ device performance.
This research was supported by the MOTIE (Ministry of Trade, Industry & Energy (#10080643) and
KSRC (Korea Semiconductor Research Consortium) support program for the development of the future
semiconductor device.
This work was also supported by the National Research Foundation of Korea (NRF) grant funded by
the Korea government (2018R1A2B6004394)

23th, session 3, speaker 11

Corrugation engineered out-of-plane polarization in 2D MoTe2
Sera Jeon1, Jaekwang Lee1
1

Department of Physics, Pusan National University, Busan, 46241, Korea
E-mail: jaekwangl@pusan.ac.kr

In general, the coexistence of electric polarity and conducting characteristics is mutually exclusive
because a finite band gap is critical to maintain the permanent electric dipole moment existing in
the polar materials. Here, using the density functional theory calculation, we find the polar
conducting feature can be developed in semiconducting monolayer 2H-MoTe2 by generating
corrugation. In particular, the out-of-plane polarization is observed even though
crystallographically there exists only in-plane polarization. We expect our results contribute tofinding optimal layered materials with giant out-of-plane polarization.

23th, session 3, speaker 12

Emergence of Kondo Resonance in Graphene Intercalatedwith Cerium
Jinwoong Hwang1, Kyoo Kim2, Hyejin Ryu1,3,4, Jingul Kim5, Ji-Eun Lee1, Sooran Kim2,5,Minhee Kang1, Byeong-Gyu Park6, Alessandra Lanzara7,8, Jinwook Chung5,9, SungKwan Mo3, Jonathan Denlinger3, Byung Il Min5, and Choongyu Hwang1,†

12

Department of Physics, Pusan National University, Busan 46241, South Korea

Max Planck-POSTECH/Hsinchu Center for Complex Phase Materials, Pohang University of Science andTechnology, Pohang 37673, South Korea
34
56Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94709, USA

Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea

Department of Physics, Pohang University of Science and Technology, Pohang 37673, South Korea

Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 37673, South
Korea
7

Materials Sciences Division, Lawrence Berkley National Laboratory and Department of Physics,
University of California, Berkeley CA 94720, USA
8

9

Department of Physics, University of California, Berkeley CA 94720, USA

Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005,
South Korea

The interaction of a magnetic impurity with surrounding electrons has been along-standing theme in modern physics to understand fundamentals of manybody effects. In particular, antiferromagnetic screening of the local magnetic
moment by conduction electrons leads to the formation of a new resonant-typemany-body ground state, so-called Kondo resonance. Here we report therealization of the Kondo resonance in a prototypical two-dimensional system,
graphene, induced by the presence of cerium with the localized spin of a 4f
electron. The combination of two complementary techniques, angle-resolved
photoemission spectroscopy and dynamic mean-field theory, reveals thedevelopment of new spectral weight near Fermi energy at lower temperature thatis hybridized with the graphene π-band. The observed T-dependence provides
not only a direct evidence of the formation of the many-body ground state ingraphene, but also novel insight how Kondo physics emerges in the sea of twodimensional Dirac electrons.

† corresponding e-mail: ckhwang@pusan.ac.kr

23th, session 3, speaker 13

Odd-parity multipoles and magneto-current eﬀect
Dept. of Phys., Hokkaido Univ.
M. Yatsushiro, S. Hayami
Multipoles have been used to represent anisotropic electric charge and current distributions in electromagnetic dynamics. Under the space-time inversion group, they are classified into four types: electric [(P, T ) = ((−1)l , +1)], magnetic [(P, T ) = ((−1)l+1 , −1)],electric toroidal [(P, T ) = ((−1)l+1 , +1)], and magnetic toroidal [(P, T ) = ((−1)l , −1)] multipoles where P and T are spatial- and time-reversal operations and l is the rank of multipoles. Recently, such multipoles have been applied to condensed matter physics, since
they describe electronic degrees of freedom, such as charge, spin, and orbital in a systematicway [1][2]. Especially, the concept of multipoles has been developed in f -electron systems
to describe strongly anisotropic nature, which results in findings of unconventional multipole
orderings, e.g., electric quadrupole ordering in PrIr2 Zn20 [3] and magnetic octupole orderingin Ce1−x Lax B6 [4]. They are also useful to understand and predict what types of physicalresponses and transport phenomena can occur. For example, magnetoelectric eﬀect where themagnetization (electric polarization) is induced by external electric (magnetic) field can becaused with rank 0-2 multipoles activated in the absence of both spatial inversion and timereversal symmetries: magnetic monopole, magnetic toroidal dipole, and magnetic quadrupole.
However, systematic descriptions of odd-parity multipoles activated in noncentrosymmetricsystems and their physical phenomena were still missing, since their formalism has not been
completed.
In the present study, we focus on odd-parity multipoles and their magneto-current eﬀect
where the magnetization is induced by electric current in metal from the microscopic viewpoint [5]. By considering the multi-orbital system with diﬀerent parities, e.g., p-d and d-f
in the noncentrosymmetric tetragonal crystal, we investigate what types of odd-parity multipoles are activated. We find the key ingredients to lead to the magneto-current eﬀect byexamining the model: the spin-orbit coupling and the onsite and oﬀsite hybridizations between orbitals with diﬀerent parities. We show that the electric dipole degree of freedom is
activated in the point group C4v by the odd-parity hybridization. It is the origin of further
unconventional physical phenomena, such as the magnetoelectric eﬀect, once the magnetic
toroidal dipole and magnetic quadrupole occurs through the electron correlation. We discuss
how these cross-correlated phenomena are induced by the multipole orderings.
[1] Y. Kuramoto, H. Kusunose, and A. Kiss, J. Phys. Soc. Jpn. 78, 072001 (2009).
[2] S. Hayami and H. Kusunose, J. Phys. Soc. Jpn. 87, 033709 (2018).
[3] T. Onimaru, K.T. Matsumoto, Y.F. Inoue, K. Umeo, T. Sakakibara, Y. Karaki, M. Kubota, and T. Takabatake, Phys. Rev. Lett. 106, 177001 (2011).
[4] R. Shiina, H. Shiba, and P. Thalmeier, J. Phys. Soc. Jpn. 66, 1741 (1997)[5] S. Hayami, M. Yatsushiro, Y. Yanagi, and H. Kusunose, arXiv: 1806.01964, (2018).

23th, session 3, speaker 14

Study on the magnetic properties of π-electrons in the Anionic
Magnetism of Rubidium Superoxide (𝐑𝐛𝐎𝟐 )Fahmi Astuti1,2, Mizuki Miyajima3, Takeshi Kakuto3, Takehito Nakano4, Isao
Watanabe1,2 and Takashi Kambe3
RIKEN Nishina Center1, Hokkaido University2, Okayama University3, Ibaraki University4

Alkalimetal superoxides, AO2 (A= Na, K, Rb, Cs) are interesting materials to study interms of their magnetic properties. The unpaired electron located in the π∗ molecular orbital of
the superoxide anion is responsible for the magnetic moment in this class of materials. Thissystem also provides rare simple manifestations of the coupling between spin, lattice, andorbital degrees of fredom in the p-electron material [1]. In CsO2, the structural phase transition
prevails from high symmetry (tetragonal) to be lower symmetry (orthorombic) by decreasingof the temperature [2]. Furthermore, by the changing of the structure, the magnetic interactionis altered from paramagnetic to low-dimensional antiferromagnetic which leads a zig-zag like1D chain along b-axis [3] followed by the formation of 3D long-range ordering below 10 K
[4]. The evidence of low-dimensional magnetism in CsO2 was also observed from high-fieldmagnetization measurement [5].
In this presentation, I summarize the result of our investigation in RbO2. Synchrotron
X-ray diffraction data in RbO2 shows the splitting of the peak indicating the existence ofstructural phase transition (detailed will be shown in the presentation). The first investigationof the microscopic magnetic nature of polycrystalline RbO2 was carried out by using
continuous muon beam. Our μSR data reveal the presence of long-range antiferromagnetic
order at below about 15 K. The high-field magnetization in RbO2 showed the absence of upturn curvature. The results from current measurements indicate the three-dimensional magnetic
interaction in this spin system.
References:[1] E. R. Ylvisaker, R. R. P. Singh, and W. E. Pickett, Phys. Rev. B 81, 180405 (2010)[2] A. Zumsteg et al., Phys. Cond. Matter 17, 267 (1974).
[3] S. Riyadi et al., Phys. Rev. Lett. 108, 217206 (2012).
[4] F. Astuti et al, to be published.
[5] M. Miyajima, F. Astuti et al., J. Phys. Soc. Jpn. 87, 063704 (2018).

23th, session 3, Invited speaker 3

Finite-size corrections to Fermi’s golden rule
Yutaka Tobita
Hokkaido University of Science,
7-15-4-1 Maeda, Teine-ku, Sapporo 006-8585, Japan
Transition probability is one of the fundamental quantities that determines
microscopic phenomena. In quantum theory, the Shrödinger equation determines the evolution in time of the states or the wavefunctions and a probabilityof a phenomenon is determined by the probability density i.e. the wavefunction.
This is the principle of probability in quantum theory. The Fermi’s golden ruleor its extension the S-matrix are very popular formulae to calculate a transition
rate or a cross section in quantum mechanics or quantum field theory. Students have already studied about them, of course [1]. They are used not only inphysics but also chemistry and biology. This is because the golden rule provides
an easy way to calculate the transition rate with plane wave states. However,that is just an approximation derived by Dirac in 1920s to calculate transition
probability [2]. Recently, we studied about finite-size corrections to the golden
rule and revealed that the corrections are not negligible in some phenomena
where particles with very small masses such as neutrinos [3] or photons [4] areinvolved. In this talk, we will showi) a brief review about the Fermi’s golden rule and its finite-size corrections, andhow to derive the transition probability in small time interval T as
P (T ) = ΓT + P d ,where P d is a constant term from finite-size corrections.
ii) Application to neutrino physics [3] and photosynthesis [5]These works are in collaboration with K. Ishikawa and N. Maeda (HU) andT. Yabuki (Hokusei Univ.)

References[1] M. L. Goldberger and K. M. Watson, Collision Theory; L. I. Schiﬀ, Quantum Mechanics; L. D. Landau and E.M. Lifshitz, Quantum Mechanics;
M. E. Peskin and D. V. Schroeder, An Introduction to Quantum Field Theory; S. Weinberg, The Quantum Theory of Fields I ; and there are manyother good textbooks.
[2] P. A. M. Dirac, Pro. R. Soc. Lond. A 114, 243 (1927).
[3] K. Ishikawa and Y. Tobita, Prog. Theor. Exp. Phys. 2013, 073B02 (2013);
Ann. Phys. 344, 118 (2014).
[4] K. Ishikawa, T. Tajima, and Y. Tobita, Prog. Theor. Exp. Phys. 2015,
013B02 (2015).
[5] N. Maeda, et. al, Prog. Theor. Exp. Phys. 2017, 053J01 (2017).

24th, session 4, Invited speaker 4

Plasmons in Atomic-scale/Nanoscale objects and Their Applications
Tadaaki NAGAO1
1

International Center for Materials Nanoarchitectonics,
National Institute for Materials Science*Email address: NAGAO.Tadaaki@nims.go.jp

Abstract.
Surface plasmon polaritons and its low-dimensional variants as well as their confined
standing waves (antenna resonances) have become increasingly important in
nanotechnology since their optical properties are strongly dependent on the size and theshape of the small objects. Because the Fermi wavelength and screening length of mostmetals are at the nanometer scale, plasmons in metals are readily tuned by tailoring theirshape, size, at the nanometer to the subnanometer scale. This closely relates to the purposeof nanotechnology which is to provide appropriate building blocks to embody nanoarchitecture with desired functions for novel electronics/photonics devices. The
propagating modes of plasmon in open structures (surfaces, nanowires, etc.) can be studied
by using electron spectroscopy and revealed a rich diversity of physics assocaiated with theelectron dynamics. On the other hand, the localized resonating modes in closed structures(particles, finite-szed rods, etc.) strongly coulples with light and exhibit wide variety of
applications in the field of nanophotonics, life science, and light harvesting technology. In
this talk I present some fundamental aspects of confined plasmons in atomic-scale andnano-scale objects. Then I also show some applications in infrared sensing using
boradband plasmonic absorbers, as wells as narrowband perfect absorbers.
lD

References[1] Tadaaki Nagao et al., Sci. Technol. Adv. Mater. 11 054506 (2010 ).
http://iopscience.iop.org/1468-6996/11/5/054506|[2] Jung-Sub Wi, Masud Rana, and Tadaaki Nagao, Nanoscale 4, 2847-2850 (2012).
[3] J.-S. Wi, L.-K. Shrestha, and T. Nagao, “ Phys. Status Solidi RRL 6, 202-204 (2012).
[4] V. M. Silkin, T. Nagao, V. Despoja, J. P. Echeverry, S. V. Eremeev, E. V. Chulkov, and P. M. Echenique,
Physical Review B 84, 165416-1 -9 (2011). doi: 10.1103/PhysRevB.84.165416[5] T. Nagao, “Chapter 9: Low-dimensional plasmons in atom sheets and atom chains,”
in Dynamics at Solid State Surfaces and Interfaces, Volume I, Edited by. U. Bovensiepen, H.
Petek, M. Wolf (Wiley VCH), pp189-211(2010). ISBN: 978-3-527-40937-2[6] T. Nagao, S. Yaginuma, T. Inaoka, and T. Sakurai, Physical Review Letters 97, 116802-1 -4(2006).

24th, session 4, speaker 15

Vortex-charging in the Abrikosov lattice
Dept. of Phys., Hokkaido Univ.1 , Dept. of Math. and Phys., Hirosaki Univ.2
M. Ohuchi1 , H. Ueki2 and T. Kita1
A number of studies on vortex-charging in type-II superconductors have been carried out
based on the mean field theory of superconductivity such as the Bogoliubov–de Gennes (BdG)
equations [1, 2]. However, the BdG equations have diﬃculties in identifying the forces responsible for the charging and also in incorporating Fermi-surface and gap anisotropies.
Recently, a study on the flux-flow Hall eﬀect has been performed [3] based on the augmented
quasiclassical equations in the Keldysh formalism with the Lorentz and pair-potential gradient(PPG) forces. On the other hand, we have derived the augmented quasiclassical equations in
the Matsubara formalism with the Lorentz and PPG forces, and calculated the core charge of
an isolated vortex using it [4]. Our results clarifies that the PPG force contributes dominantly
to charging in the core region of an isolated vortex over a wide parameter range such as thetemperature and magnetic-penetration-depth. However, the previous studies have also shownthat the charge accumulation originating from the Lorentz force is enhanced substantially infinite magnetic fields [5]. This indicates that the Lorentz force contribution may become
dominant over the PPG force contribution in finite magnetic fields.
We study the vortex-charging in the Abrikosov lattice due to the Lorentz and PPG forces
to see which forces dominantly contribute to the charging in finite magnetic fields.

[1] M. Matsumoto and R. Heeb, Phys. Rev. B 65, 014504 (2001).
[2] M. Machida and T. Koyama, Phys. Rev. Lett. 90, 077003 (2003).
[3] E. Arahata and Y. Kato, J. Low Temp. Phys. 175, 346 (2014).
[4] M. Ohuchi, H. Ueki, T. Kita, J. Phys. Soc. Jpn. 86, 073702 (2017).
[5] W. Kohno, H. Ueki, and T. Kita, J. Phys. Soc. Jpn. 85, 083705 (2016).

24th, session 4, speaker 16

Fabrication and characterization of sputter iron-based film
for energy applications
Hai Dang Ngo1, 2, Thien Duc Ngo1, Kai Chen1,3, Akemi Tamanai1, Orjan S.
Handegard1, 2, Naoto Umezawa1, and Tadaaki Nagao1,2.
12International Center for Materials Nanoarchitectonics, National Institute forMaterials Science, Tsukuba 305-0044, Japan

Department of Condensed Matter Physics, Graduate school of Science, Hokkaido
University, Kita-10 Nishi-8 Kita-ku, Sapporo 060-0810, Japan

3

Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China

Abstract: Iron (III) titanates are composed of earth abundant elements and are
attracting rapidly growing interest as highly promising candidates for the solarenergy applications such as photodegradation, solar-water splitting, andphotovoltaics. In this article, we report a successful synthesis of orthorhombic
pseudobrookite Fe2TiO5 thin films with RF sputtering followed by post deposition
annealing in air at 550oC. Chemical composition, crystal structure, surface
morphology, and optical properties of the synthesized films were experimentally aswell as theoretically characterized with X-ray diffraction (XRD), X-ray
photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic
force microscope (AFM), Raman scattering spectroscopy, and UV-Vis absorption
and DFT simulation. The film was confirmed to be single phase, and exhibited highcrystallinity orthorhombic pseudobrookite structure with a preferential crystal
orientation of (331) with excellent adhesion on both glass and silicon substrates.
Comparison of dielectric functions between spectroscopic ellipsometry and DFT
simulation showed good matching. Estimated direct and indirect band gap values
from the optical characterization also well understood in comparison with theenergy band diagram from DFT simulations.
Keywords: Iron Titanate, Fe2TiO5, RF magnetron sputtering, optical properties,
pseudobrookite, DFT calculation

24th, session 4, speaker 17

The Electronic Specific heat in the Superconducting State of a Bismuth Sulfide
Superconductor
Y. Wang, S. Takahashi, T. Suda, T. Tamura, H. Ohta, N. Momono
Muroran Institute of Technology, Muroran, 050-8585, Japan
In recent years, breakthrough discoveries have focused layered materials in the field of
new superconducting materials. Especially the superconductivity in LaOxF1-xBiS2 compounds
attracted the attention of physicists. The characteristic structure is an alternate stacking ofsuperconducting BiS2 layers and blocking layers (LaO/F) for supplying electrons. The layered
crystal structure is analogous to those of high-temperature (high-Tc) cuprate and Fe-based
superconductors. The mechanism of the superconductivity in BiS2 superconductors have notbeen clarified yet.
As is well known, the symmetry of the superconducting gap reflects the origin of thesuperconducting mechanism. The magnetic penetration depth measurements and specific heatmeasurements for the La-based and Nd-based BiS2 superconductors have indicated the full
gap with s-wave [1-3]. However, angle-resolved photoemission spectroscopy (ARPES)
measurements suggested the large superconducting-gap anisotropy and attracted muchattention [4]. Recently, the point contact spectroscopy measurements suggested the gap
symmetry is unconventional pairing symmetry [5]. In order to clarify superconducting gap
symmetry and bulk nature of superconductivity, we investigated the superconductivity by
specific heat measurements.
Single crystals of LaO1-xFxBiS2 (x = 0.5, 0.4) were grown by using CsCl/KCl-flux method
under ambient pressure. The specific heat was measured in the temperature range of
0.3K~10K (PPMS). Shown in Fig. 1 is the temperature dependence of electronic specific heat.
The electronic specific heat was obtained bysubtracting the lattice contribution βT3 fromthe total specific heat C (T). There is a clear
jump
that
corresponds
tothesuperconducting transition appeared in the x= 0.5. The presence of the jump clearly
indicatesthebulk
natureofsuperconductivity. Besides, when x = 0.4,
the jump is not clear. The transition area has
become broadly. It’s behavior expected thebulk like of superconductivity in thiscompound. In the low temperature, the datafor x = 0.5 (red line) is going to zero, but theother line is uncertainty. At the same time,
the Tc has got little suppression. For the x =0.5 sample, it fits well with BCS theory andthe energy gap is full gap with s-wave in Fig. 1. T dependence of electronic specific heat Ce/T
weak-coupling limit.
References[1] G. Lamura et al., Phys. Rev. B 88, 180509(2013)[2] T. Yamashita et al., J. Phys. Soc. Jpn. 85, 073707 (2016).
[3] N. Kase et al., Phys. Rev. B 96, 214506(2017).
[4] Y. Ota et al., Phys. Rev. Lett. 118, 167002 (2017).
[5] F. Giubileo et al., J. Phys. Chem. Solids. 014 (2018).

24th, session 7, Invited speaker 5

Application of graphene and carbon nanotube -based heterostructures
Haeyong Kang1, Jeongmin Park2, Jeong-Gyun Kim2, and Dongseok Suh2
12

Department of Physics, Pusan National University, Busan 46241, Korea

Department of Energy Science, Sungkyunkwan University, Suwon 16419, Korea

Carbon based materials have attracted significant attention, with structures of various
dimensionalities such as, diamond and graphite in 3 dimension (3D), graphene in 2D, carbon
nanotube (CNT) in 1D, and fullerene in 0D. Among them, we have systematically studied graphene
and CNT for their interesting physics and possibility of wide application. In our studies, graphene
conductance is found to be very sensitive to the change of the properties of oxide films underneath.
The charge neutral point and quantum Hall states in graphene can be good indicators for probing
the oxygen vacancy mechanism of thin film
In addition, I will also introduce the application and interesting properties of CNT sheets and yarns.
CNT sheets were drawn from CNT forest where CNTs were grown densely and vertically. Freestanding CNT sheets consist of highly aligned but weakly entangled long bundles of CNT fibrils byvan der Waals force without use of a binder. Due to their aerogel-like structure, CNT sheets showhigh flexibility, porosity and light weight, and can be stretched up to 600% on top of elastomer
without damage of CNT sheets. Because the resistance does not vary during elongation-relaxation
cycles, the application of stable stretchable conductor and high-performance heaters can behighlighted. Another strong point of CNT sheets is easy adaptation of other materials, which makes
it possible to use as a flexible superconducting yarns.

24th, session 7, speaker 18

An introduction to String Theory
Cristopher Arturo Chuñe Sosa1
1

Department of Physics, Hokkaido University, Sapporo, Japan

One approach leading to the unification of quantum gravity and quantum field theory is
by changing the way in which we describe the elementary particles. If instead of using thepoint-like description of particles, we state that these actually have some structure, i.e.
as a one dimensional object called string, then the oscillation modes of the strings will be
how we start formulating the particles of the standard model and the graviton.
Consequences of this apparently trivial change also provide some solution to existing
issues contained in field theory as well as some new features which can be treated withsome mathematical ideas. In this opportunity, the fundamental ideas and features of thesuperstring theory will be presented in an intuitive way.

1

24th, session 7, speaker 19

Single particle Raman scattering spectroscopy fromnano/micro bismuth droplets on SiØrjan Sele Handegård1,2, Masahiro Kitajima1 and Tadaaki Nagao1,2
International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science(NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan2
Department of Condensed Matter Physics, Hokkaido University, Kita, Sapporo, Hokkaido 060-0808,
Japan
E-mail: Tadaaki.Nagao@nims.go.jp

1

Abstract
Group V semimetals show exotic wavelength dependent optical response such as metal/dielectric duality, andoffers unexplored possibilities in photonics and plasmonics research. There is a growing interest in bismuth(Bi), as it has many unusual properties, such as a Dirac-like band dispersion, smaller effective mass, very low
carrier density, and longer mean free path compared to many other elemental metals. Majority of the works
reported on Bi so far has mainly focused on bulk crystal or thin films.
In this presentation, we report the fabrication of single-crystalline nano/micrometer-sized well defined Bi
hemispherical droplets and their structural and optical characterization using SEM, AFM, dark-field microscopy
and confocal Raman microscopy. Bi droplets were formed by post-process annealing of an epitaxially grown Bi
film in ultra high vacuum on Si(111). The crystallinity of the films and the subsequent droplet formation wasmonitored in situ by reflection high energy electron diffraction.
We observed that at the position of the pristine Bi droplets, the Si Raman signal (at 520 1/cm) from the substrate
is reduced due to a shadowing/blocking effect by the Bi hemispheres. However, after exposing these Bi droplets
to laser irradiation (785 nm, 30 mW/cm2), the Si Raman signal becomes stronger at the Bi positions, comparedto the intensities before laser exposure. The average relative enhancement factor showed a size dependence andranged from 1.4-10.1 for a selection of droplets with increasing width. To our knowledge, this is the first timesuch a phenomenon is reported from a group V semimetal. The mechanism of Si phonon enhancement
resembles SERS effect, but is not yet fully understood. We will continue investigating the correlation between
the crystallinity, microfacets/roughness at the Bi surfaces, and light trapping/absorption effects together with theelectromagnetic near-field enhancements.

Figure 1. Effect of laser processing on Bi and Raman scattering. SEM image of Bi droplets (I) and Si 520
1/cm Raman mapping (II) before (a) and after (b) laser processing. Images are obtained from the same area.

24th, session 7, speaker 20

electron-electron interaction in graphene decorated withytterbium
Minhee Kang1, Jinwoong Hwang1, Ji-Eun Lee1, Alexei Fedorov2, andChoongyu Hwang1*
1 Department of Physics, Pusan National University, Busan 46241, Korea
2 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94201, USA

The presence of ytterbium leads to enhanced electron-phonon coupling in graphene strong
enough to possibly realize superconductivity above ~1 K. The origin of the strong enhancement
has been studied using angle-resolved photoemission spectroscopy. The electron band structure
shows that of both heavily and lightly electron-doped graphene. The former shows theenhanced electron-phonon coupling compared to that of as-grown graphene, while the latterprovides an evidence of enhanced electron-electron interaction. The strong enhancement ofelectron-phonon coupling in graphene decorated with ytterbium is attributed to theconcomitantly enhanced electron-electron interaction.

24th, session 7, Invited speaker 6

The Study of Electronic Charge Order in a Bismuth Based Cuprate
Superconductor Using Scanning Tunneling Microscopy/Spectroscopy
N. Momono1, K. Kawamura1, Y. Yokota1, H. Ohta1, T. Kurosawa2, M. Oda2, M. Ido2
1

Muroran Institute of Technology, Muroran, 050-8585, Japan
2
Hokkaido University, Sapporo, 060-0808, JapanThe superconducting transition temperature Tc is one of the most important parametersof superconductors. The Tc of high-temperature cuprate superconductors depends on holeconcentration p. The typical p-dependence of Tc for cuprate superconductors is adome-shaped Tc-p curve. The La-based cuprate superconductors such as La2-xBaxCuO4 andLa2-x-yNdySrxCuO4 exhibit an anomalous "dip" feature near p~1/8 on the Tc-p curve, which isso-called "1/8 anomaly" of Tc. The 1/8 anomaly is due to the formation of a stripe structurewith antiferromagnetic and charge orders. It is still unclear how the stripe order coexists with
the High-Tc superconductivity in cuprates.
Recently it was reported in the scanning tunneling microscopy/spectroscopy
experiments and the resonant X-ray scattering experiments that the checkerboad-like chargeorder occurs in Bi2Sr2CaCu2O8+G (Bi2212), Bi2Sr2CuO6+G (Bi2201) and YBa2Cu3O7 (YBCO)
cuprate superconductors [1, 2]. In YBCO, it was also reported that the Tc plateau aroundTc~60K is related to the appearance of the charge order. On the other hand, it was reported in
Zn-doped Bi2212 that Zn-doping induces a dip feature on Tc-p curve [3], although there is noreport about an anomaly on the Tc-p curve in pure Bi2212.
In the present study, we report that Tc is anomalously suppressed p~1/8 in
Bi2Sr2Ca1-xDyxCu2O8+G (Dy-Bi2212). In the scanning tunneling microscopy/spectroscopy(STM/STS) experiments on Dy-Bi2212 with p~1/8, the checkerboard-like charge orderappears at around a wave vector qCO~0.3 rlu. In the STS spectrum, no well-defined coherent
peak is observed. The dip of the Tc-p curve induced by the substitution of Dy in Bi2212 wassimilar to that observed in Zn-doped Bi2212, suggesting that the suppression of Tc near p~1/8
in Dy-Bi2212 is related to the pinning of the charge order.
References[1] T. Kurosawa et al., Phys. Rev. B 81, 094519(2010), J. Phys. Soc. Jpn 85, 044709(2016).
[2] J. Chang et al., Nat. Phys. 8, 871 (2012)[3] M. Akoshima et al., Phys. Rev. B 57, 7491(1998).

24th, session 8, speaker 21

Observation of the chemical potential shift in SnSe by Ta
adsorption
Ji–Eun Lee1, Jinwoong Hwang1, Minhee Kang1, Kyoo Kim2, Hyejin Ryu2,3, Shujie Tang3,
Dung Anh Tuan4, Sunglae Cho4, Sung-Kwan Mo3, Ho-soon Yang1*,
and Choongyu Hwang1**Email of corresponding authors: hsyang@pusan.ac.kr and ckhwang@pusan.ac.kr
1
2

Department of Physics, Pusan National University, Busan 46241, South Korea

Max Planck-POSTECH/Hsinchu Center for Complex Phase Materials, Pohang University of

Science and Technology, Pohang 37673, Korea
3

Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94210, USA
4

Department of Physics, University of Ulsan, Ulsan 680-749, South Korea

SnSe shows an excellent thermoelectric effect, of which efficiency (ZT) reaches up to 2.6 and2.8 by hole and electron doping, respectively. The strong enhancement of ZT is attributed tomulti-valley valence bands and strong anharmonicity of phonons. The former is responsible
for the drastic change of charge carrier density upon substituting Sn with foreign atoms orcreating Sn vacancies. Using angle-resolved photoemission spectroscopy, the change of charge
carrier density has been investigated via the modification of the electron band structure of
single crystal SnSe by foreign atoms. Tantalum adsorption results in the chemical potential
shift by ~0.3 eV that roughly corresponds to the charge carrier density with maximum ZT. This
result suggests an alternative way to control the thermoelectric effect that will provide a viable
route towards the realization of high thermoelectric performance.

24th, session 8, speaker 22

Magnetic proximity effect in Nd1-xSrxMnO3 multilayers
SangKyun Ryu1, Hyegyeong Kim2, Jinhyung Cho3, Hyoungjeen Jeen*1
1
2
3

Department of Physics, Pusan National University, 46241

Core Research Facilities, Pusan National University, 46241

Pusan National University, Department of Physics Education, 46241

Abstract

It is well-known that the change of stoichiometry changes physical properties easily inmanganites. We grew two kinds of Nd1-xSrxMnO3 thin films with different stoichiometry by oxygen
partial pressure control. We grew multilayers by stacking foregoing Nd1-xSrxMnO3 with differently
hole-doped Nd1-xSrxMnO3 (x ~ 0.5 and 0.3) as sublayers. The formation of multilayers without changeof lattice constants is confirmed by x-ray diffraction. Detailed magnetic characterization shows theenhancement of magnetic moments in multilayers to comparing with single layer. Also, when the
thickness of each layer is decrease in multilayers, magnetic moment of multilayers is more enhanced.
This result clearly indicates smearing of ferromagnetism into the less-magnetic layers at the interfaces.
We suggest polarized neutron reflectivity experiment toapprove the role of interface at multilayer films. This
interfacial magnetism is useful to design magnetic
oxides with high magnetic moments. This work was
supported by the Basic Science Research Program
through the National Research Foundation of Korea(NRF) funded by the Ministry of Education (NRF2015R1D1A1A02062175).

24th, session 8, speaker 23

Enhancement of magnetic properties in M-type Sr-hexaferrite

Lien Phuong Nguyen, Jaekwang Lee
Department of Physics, Pusan National University, Pusan 46241, Korea

Hexagonal strontium hexaferrite (SrFe12O19) is commonly used as permanent
magnets. Recently, there have been many attempts to further enhance the magnetic
properties of Sr-hexaferrite with various cationic substitutions. Here, using the afirst-principles density functional theory calculations, we studied the effect of codoping with Ca-X (X = La, Gd, Y, Al) on the electronic property and total magnetic
moment in Ca2XSr(Fe12O19)4. The initial result shows a little change in the totalmagnetic moment of the Ca2XSr(Fe12O19)4, which comes from the magnetization
enhancement in Fe3+ sites due to the redistribution of excess charge brought by the
dopant.

24th, session 8, speaker 24
Contribution of Quantum Effects on the Muon Site Calculation of La2CuO4
M. R. Ramadhan1,2, I. Ramli1,3, M. D. Umar1,3, S. Winarsih1,2, B. Adiperdana1,5,
B. Kurniawan2, M. I. Mohamed-Ibrahim4, S. Sulaiman4, T. Adachi6, I. Watanabe1,2,3,4
1

Meson Science Laboratory, RIKEN Nishina Center, Wako 351-0198, Japan2
Department of Physics, Universitas Indonesia, Depok 16424, Indonesia
3
Department of Condensed Matter Physics, Hokkaido University, Sapporo 060-0810, Japan
4
School of Distance Education, Universiti Sains Malaysia, Penang 11800, Malaysia
5
Department of Chemistry, Universitas Padjajaran, Sumedang 45363, Indonesia
6
Department of Engineering and Applied Sciences, Sophia University, Tokyo 102-8554,
Japan
The muon spin relaxation (µSR) method is a powerful tool to investigate electronic states of
the Cu-based high-TC superconducting oxides. To get a better understanding of themagnetically ordered state of La2CuO4 (LCO), muon positions information is required.
Although several attempts have been made in the past, any unified methods to investigate
muon positions have not yet been firmly established. For this reason, the PSR results achievedon LCO, even in the early stage of the high-TC history, have not yet been fully explained[1-3]. We are approaching this matter by using the density functional theory (DFT)
calculation method. The on-site Coulomb repulsion energy, U = 8 eV, was taken into accountto include the correlation energy between the 3d orbitals of neighboring Cu atoms. Threeminimum potential positions were estimated from the calculations and set to be the initial
muon-stopping positions. In subsequent calculations, one muon, which effectively act as adilute charged impurity, was introduced into a supercell structure. The supercell contains
32-unit cells formed by the inclusion of 4-unit cells along a and b-axis, and 2 cells along
c-axis. The supercell structure was then relaxed until the forces between the ions are below
convergence threshold. From our current results, the magnetic moment on the nearest Cu
atom in the perturbed system was slightly lowered by the presence of muon, while the rest of
the magnetic moment shows a relatively similar value with the unperturbed system. This local
deformation caused by the muon was taken into account along with the zero-point vibration
motion of muon to calculate dipole fields at the muon positions. The results of ourinvestigations will be presented.

Fig. 1: Comparison of CuO6 octahedra after the relaxation of lattice structure and the muon positionin the case of (a) without the muon and putting the muon at initial minimum potential positions of (b)M1, (c) M2 and (d) M3.

References[1] R. Saito et al., Physica C 185-189, 1217 (1991).
[2] S. B. Sulaiman et al., Phys. Rev. B 49, 9879 (1994).
[3] H. U. Suter et al., Physica B 326, 329 (2003).

24th, session 8, Invited speaker 7

1HZʌ-d interaction systems in the organic conductors
Noriaki Matsunaga,
Department of Physics, Hokkaido University
Email: mat@phys.sci.hokudai.ac.jp
The ʌ-d interacting system has been has been one of the most attractive topics in the organic
conductors. Especially, the ʌ-d interacting system Ȝ-(BETS)2FeCl4 becomes an antiferromagnetic (AF)phase at zero magnetic field and a field induced superconductivity above 17 T [1], which is explainedby the Jaccarino-Peter compensation mechanism [2]. In contrast, Ȝ-(BETS)2GaCl4 shows
metal-superconductivity transition at 5.5 K [3]. Therefore, the AF phase of Ȝ-(BETS)2FeCl4 is thought
to be induced by the existence of 3d spins of the FeCl4 anion. On the other hand, Ȝ -(BETS)2GaBr4
shows the metal-insulator transition at 50 K with magnetic anomaly [4]. To clarify the role of the 3dsSLQV DQG WKH ʌ-d ,QWHUDFWLRQ LQ WKH Ȝ- DQG Ȝ¶ salts, we investigate quasi-two dimensional organic
conductors
Ȝ-(BEDT-STF)2GaCl4,
Ȝ-(BEDT-STF)2FeCl4,
Ȝ -(BEDT-STF)2GaBr4,andȜ -(BEDT-STF)2FeBr4.
From the resistivity measurements under pressure and magnetic field, we found that the Ȝ- and Ȝ BEDT-STF salts are located at the lower pressure region than the Ȝ- and Ȝ - BETS salts. Figure 1 shows
the universal phase diagram of Ȝ-type family. Ȝ-(BEDT-STF)2GaCl4 does not show the AF phase atambient pressure even though it shows the strong AF interaction [5]. On the other hand,Ȝ-(BEDT-STF)2FeCl4 shows the AF
transition in the ʌ-spin system at 16 K
[6]. These results suggest that the AF
state of the ʌ-electron system in the
BEDT-STF layers is stabilized by the
3d spins on FeCl4 anions through theʌ-dinteraction.
The
magnetic
susceptibility of Ȝ-(BEDT-STF)2FeCl4
at ambient pressure can be fit the AFordered ʌ-spin model [7]. Therefore,thegroundstateofȜ-(BEDT-STF)2FeCl4
atambient
pressure is thought to be the AF orderedstate. Moreover, the relation between
the static susceptibility and the splittingof the NMR shift suggests the existenceof the relatively strong díd AF
interaction. Therefore, the ʌ-d and d-dd-spininteractions show the significant role incontent
the ground state of this pressure regionof Ȝ-type family.
Fig. 1. Universal phase diagram of Ȝ-type family.
References[1] Uji, S. et al. Nature., 410, 908 (2001).
[2] V. Jaccarino and M. Peter, Phys. Rev. Lett., 9, 290 (1962).
[3] H. Kobayashi, et al. Chem. Lett., 22 2179, (1993).
[4] Tanaka, H. et al. Chem. Lett., 28 133 (1999).
[5] Minamidate, T. et al. JPSJ, 84, 063704 (2015).
[6] Minamidate, T. et al. Phys. Rev. B 97, 104404 (2018)[7] Akiba, H. et al. JPSJ, 80, 063601 (2011).

25th, DC Midterm, speaker 25
Study of Microscopic Magnetism in YBa2Cu3O6 by μSR and DFT
Irwan Ramli1,2, S. S. Mohd-Tajudin3, M. R. Ramadhan1,4, M. I. Mohamed-Ibrahim3,
S. Sulaiman3, T. Nishizaki5, B. Kurniawan4, and I. Watanabe1,2,3,4
1

Meson Science Lab., RIKEN Nishina Center, 2-1 Hirosawa, Saitama 351-0198, Japan,
2
Department of Condensed Matter Physics, Graduate School of Science,
Hokkaido University, Kita-ku, Sapporo 060-0810, Japan,
3Computational Chemistry and Physics Laboratory, School of Distance Education,
Universiti Sains Malaysia, Penang 11800, Malaysia,
4
Department of Physics, Universitas Indonesia, Depok 16424, Indonesia,
5
Department of Electrical Engineering, Kyushu Sangyo University, Fukuoka 813-8503, Japan.

The antiferromagnetic (AF) interactions in Cu-based high-TC superconductors is the key tounderstand the mechanism of high-TC superconductivity. YBa2Cu3O6 (YBCO6) is the mothersystem of the Y-system high-TC superconductor. This system is well known as Mott insulator
with the long-range AF ordering with TN = 350 K.1 The AF ordering disappears withincreasing doped holes introduced by additional oxygen and the superconductivity appears.2
We utilized the muon-spin relaxation (μSR) technique to study the microscopic electronic andmagnetic properties of YBCO6. The μSR is extremely sensitive to probe the local magnetism
due to the large gyromagnetic ratio of the muon spin.3 But it has difficulties in investigating
quantitative information of hyperfine interactions due to the unknown positions of the injectedmuons in the materials and complicated local perturbation caused by the muons to its
surroundings.4
We are developing research method to address thoseissues by using density functional theory (DFT)
calculations. As the muon has positive charge, it prefers to
M1stop at a local minimum potential position in materials.
M2
We found three possible initial muon sites in YBCO6
marked as M1, M2 and M3 as shown in Fig. 1. In order toM3
investigate local perturbations caused by the muon as adilute charged impurity, we modeled a supercell whichcontains 32 unit cells, 4 unit cells along a- and b-axis and2 unit cells along c-axis, and only one muon. We thencalculated relaxations of the atomic positions throughout
Fig. 1: Possible initial
the whole the supercell. We also included changes in themuon stopping positions inlocal electronic states and the spatial distribution of spin
YBCO6 estimated from ourdensity of surrounding electrons. Taking into account theDFT calculations. The
zero-point vibration energy of the muon, and comparing
yellow area indicates thewith μSR experimental data, we reveal information about
isosurface at 500 meV.
muon positions and its surrounding electronic state.
References[1] J. M. Tranquada et al., Phys. Rev. B 38, 2477-2485 (1988).
[2] Y. Koike et al., J. Phys. Soc. Jpn. 85, 091006 (2016).
[3] S. Sanna et al., Phys. Rev. Lett. 93, 2017001 (2004).
[4] J. S. Möller et al., Phys. Scr. 88, 068510 (2013).

25th, DC Midterm, speaker 26
Magnetically ordered states in hole-doped pyrochlore iridate Y2Ir2O7
J. Angel1, 2, H. Nomura3, T. Taniguchi3, K. Matsuhira3, I. Watanabe1, 2
1
RIKEN Nishina Center, 2Hokkaido University, 3Kyushu Institute of Technology
Pyrochlore iridates, R2Ir2O7 (R=Y and lanthanides), are worthy to bestudied because of its frustrated
magnetic interactions. Y2Ir2O7 ispredicted to be a Weyl semimetal
followed by the metal-insulatortransition (MIT) around 170 K and withan all-in all-out magnetic ground state[1,2]. Since the Y atom does notpossess a local magnetic moment, themagnetic properties of Ir moment whichplay an important role in exotic
electronic states in R2Ir2O7 can bedirectly investigated. Moreover, thehole-concentration dependence on themagnetic properties can be clarified
including a quantum critical behavior
from the semiconducting to metallic
states [3].
The MIT of (Y1-yCuxCay)2Ir2O7
at variable y fixing x which involves theantiferromagnetictransition
is Figure 1. Zero-field time spectra of Y2Ir2O7 and its hole-doped
suppressed compared to that observed compounds.
in the non-doped sample by Cu- andCa-doping. In order to approach to investigate magnetically ordered states of hole-doped
Y2Ir2O7, I applied the muon-spin relaxation method. Figure 1 shows the temperaturedependence of the muon-spin relaxation rate measured at (Y1-yCuxCay)2Ir2O7. Changes in themagnetic properties and a phase diagram as the effect of Cu and Ca substitution will be
discussed.

References:[1] W. K. Zhu et al., Phys. Rev. B 90, 054419 (2014).
[2] H. Fukazawa and Y. Maeno, J. Phys. Soc. Jpn. 71, 2578 (2002).
[3] L. Savary, E. Moon and L. Balents., Phys. Rev. X 4, 041027 (2014).
[4] W. Witczak-Krempa et al., Cond. Matter. Phys. 5: 57-82 (2014).
[5] S.M. Disseler et al., Phys. Rev. B 86, 014428 (2012).

25th, DC Midterm, speaker 27

Manipulating artificial plasmonic heterostructures tocontrol spectrally selective absorption and emission in theinfrared region
Tung Anh Doan1, 2, Thang Duy Dao1, Satoshi Ishii1 and Tadaaki Nagao1,2.
12International Center for Materials Nanoarchitectonics, National Institute forMaterials Science, Tsukuba 305-0044, Japan

Department of Condensed Matter Physics, Graduate school of Science, Hokkaido
University, Sapporo 060-0810, Japan

Abstract: The optical properties of natural materials essentially depend on their chemicalcompositions rather than their sample sizes. Artificial plasmonic heterostructures are made up of
ensembles of sub-wavelength building blocks known as meta-atoms. These artificial materials reveal a
different and fascinating picture: manipulation of geometrical parameters and arrangement of metaatoms changes their optical properties dramatically. In this work, we demonstrate the ability to control
spectrally selective IR absorption and emission by coupling the fundamental electric-magnetic
resonance mode of a metal-insulator-metal (MIM) disk array resonator and incident waves. As a proof
of concepts, a MEMS-based hybrid multi-color plasmonic-pyroelectric infrared detector wasdemonstrated experimentally to selectively absorb IR radiation at 3.5, 3.9, 4.3 and 4.7 µm. Alternatively,
we also fabricated a spectrally selective multi-color thermoelectric detector, which combines theconcepts of a MIM disk array resonator and a Si-based thermoelectric transducer to selectively absorb
IR radiation at 3.5, 3.9, 4.3 and 4.7 µm. However, these subwavelength patterned structures require
high-precision and multi-step lithography, which poses many challenges for fabrication on large scaleor curved surfaces. To overcome this problem, we proposed to couple incident IR light at very narrowabsorption band utilizing planar asymmetric Fabry-Perot cavities in two forms: plain metal-dielectricmetal (MDM) and [distributed Bragg reflector]-dielectric-metal (DDM). As a proof of concept, werealized an Au-Al2O3-Au based spectrally selective emitter and a hybrid 3(SiO2-Si)|SiO2|Al-based
pyroelectric detector with high-resolution spectroscopy, flexible tunability, and lithography-freefabrication. For practical applications, spectrally selective multi-color detectors can be used inpyrometry to yield accurate temperature measurement of non-greybody objects. Inherent emissivity
characteristic of non-greybody objects is one of the most challenging parameters to manage to ensure
accurate temperature measurement. However, the usage of a pre-determined emissivity value or analytic
fitting functions often leads to unexpectedly catastrophic temperature errors. To circumvent thisproblem, we proposed a novel approach using artificial intelligence (AI) algorithm, specifically artificial
neural networks, This approach promises to extract the true temperature of non-gray surfaces frommulti-color pyrometers with much higher accuracy.

Keywords: plasmonic, meta-atom, spectrally selective, emitter, detector, multicolor pyrometry,temperature-emissivity separation, artificial neural network

25th, DC Midterm, speaker 28

Exploring Optical and Thermal Properties of Non-noble Metal Plasmonic Structures
Manpreet Kaur1,2, Satoshi Ishii1*, Satish Laxman Shinde1, Thang Duy Dao1 and Tadaaki Nagao1,2*1International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science(NIMS), Tsukuba, Ibaraki, 305-0044, Japan
2Department of Condensed Matter Physics, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan

Non-noble metal plasmonic materials have been attracting significant attention both in applied andfundamental researches. For example, titanium nitride (TiN) is a typical refractory ceramic and is
attracting significant interest for photothermal applications in industry. Gallium (Ga)nanostructures is also drawing attention as temperature-tuneable plasmonic element operative inthe ultraviolet to the infrared region. The lossy plasmonic resonance of TiN nanoparticle are broad
enough to cover visible to near infrared region of the solar spectrum. We have fabricated solarheat converting devices with titanium nitride nanoparticles loaded on ceramic wool and in porousalumina for floatable water distillation devices and achieved high photothermal performances [1][2]. Among the ultraviolet materials, gallium stands out for its complementary material properties

compared with the noble metal nanoparticles (NPs) [3]. Unlike Au or Ag, Ga has a Drude-likedielectric function extending from the vacuum ultraviolet through the visible and, in the liquidstate, into the infrared spectral region. The experiment and electromagnetic simulation are
combined to study the optical response of a single Ga nanostructures (nanoparticles and nanowires)of various diameters and length based upon its temperature-dependent optical constants.
This study experimentally suggests the use of non-noble metal plasmonic materials based upon
the previous theoretical predictions of plasmonic behaviour of TiN and Ga.
[1]
S. Ishii, R. P. Sugavaneshwar, T. Nagao, The Journal of Physical Chemistry C 2015.
[2]
M. Kaur, S. Ishii, S. L. Shinde, T. Nagao, ACS Sustainable Chemistry & Engineering 2017, 5, 8523.
[3]
M. W. Knight, T. Coenen, Y. Yang, B. J. Brenny, M. Losurdo, A. S. Brown, H. O. Everitt, A. Polman,
ACS nano 2015, 9, 2049.

(2) Poster Presentations

24th of July
@Academic rounge 1 & 2 in the faculty of engineering (10:50 ~ 12:10 )24th, session 6, poster 1

Competing magnetic phases emerged under magnetic field in triangularlattice dimer Cs3 Fe2 Cl9
1

Y. Ishii, 2 Y. Matsushita, 1 H. Yoshida, 1 M. Oda, 3 M. Hagihala, 4 T. Masuda, 5 T. Kida,
5

1

Y. Narumi, and 5 M. Hagiwara.

Dept.of Phys.Grad .Sch.Sci ., Hokkaido Univ ., 2 National Institute for Material Science,
3

KEK − IMSS , 4 ISSP , 5 AHMF .Dept.of Phys.Grad .Sch.Sci .Osaka Univ .

A3 M2 X9 has the crystal structure which contains triangular lattices consist of the M ion dimers, and thetriangular lattices stack along the c-axis in a hexagonal stacking manner (Figure 1(a)). In A3 M2 X9 , there arethree interactions J0 (intra-dimer interaction), Jp (inter-dimer interaction within the triangular layer) and Jc(inter-dimer interaction between the triangular layers) as shown in the Figure 1(b) and (c). The competition ofthese interactions often evokes interesting magnetisms including magnetization plateau and spin singlet groundstate [1-4]. In the previous study of Cs3 Fe2 Cl9 , only the magnetic susceptibility of the powder sample was reported,
therefore, the ground state of Cs3 Fe2 Cl9 has not been understood well yet [5]. We succeeded synthesizing thesingle crystals of Cs3 Fe2 Cl9 , and we studied the magnetic properties of the compound by means of a magnetic
susceptibility, a heat capacity, a high field magnetization and an elastic neutron scattering on the single crystals.
The magnetic susceptibility revealed that Cs3 Fe2 Cl9 was S = 5/2 antiferromagnet (AFM) (ΘW = - 20.1 K), andour analysis indicated antiferromagnetic J0 = - 2.3 K and the average of the out of dimer interactions Jp + Jc = 0.7 K were comparable with each other. The magnetic susceptibility exhibited a sudden drop at TN = 5.3 K below
1 T at which a very steep peak appeared in the heat capacity. The sharpness of the anomalies indicates that a 1storder transition occurs at TN . We found that the magnetic state below TN was quite sensitive to magnetic field.
Under the magnetic field applied parallel to the c-axis, Cs3 Fe2 Cl9 shows field induced successive phase transitions
such as meta-magnetic transitions with hysteresis and MS /2 magnetization plateau, which is probably due tothe comparable energy scale of the J0 , Jp , Jc , spin anisotropy, and magnetic field. Finally, we obtained the rich
H − T magnetic phase diagram under H // c-axis as summarized in Figure 1(d). The neutron diﬀraction in thezero-magnetic field revealed that the ground state was the stripe type magnetic ordered state which was same as
the spin structure of the ground state of the buckled honeycomb lattice AFM Ba2 NiTeO6 [6].
Therefore, Cs3 Fe2 Cl9 is regarded asbuckled honeycomb AFM rather than
the triangular lattice dimer system
magnetically. In my presentation, I
will introduce the detail experimental results and discuss the interesting
magnetic properties of Cs3 Fe2 Cl9 .
(b)

(d)

References[1] B Leuenberger etal., Chem. Phys.
Lett. 126, 255-258 (1986).
[2] B Leuenberger etal., Inorg. Chem.
25, 2930-2935 (1986).
[3] B Leuenberger etal., Solid State
Chem. 64, 90-101 (1986).

(c)[4] T. Ziman etal., Phys. Soc. Jpn.
74, 119-128 (2006).
[5] A. P. Ginsberg etal., Inorg. Chem.
2, 817-822 (1963).
[6] S. Asai etal., Phys. Rev. B 93,
024412 (2016).

Fig. 1:(a)The perspective view of the crystal structure of

Cs3 Fe2 Cl9 . (b)(c)The magnetic interaction passes in Cs3 Fe2 Cl9 .
(d) H − T magnetic phase diagram of Cs3 Fe2 Cl9 .

1

24th, session 6, poster 2

Ground-State Wave Function of the Fermion-Boson
Mixtures with Fermion-Boson Interactions
Dept. of Phys., Hokkaido Univ.
W. Kouno and T. Kita
Quantum statistical physics on the basis of second quantization is the most fundamental
idea for considering many-body systems. This method is supported by the assumption thatthe considering system is composed of same particles with permutation symmetry (bosons) orantisymmetry (fermions). On the other hand, there also exist mixed systems with diﬀerent
kinds of particles. In such systems, many-body correlations between diﬀerent particles bringabout nontrivial phenomena, such as superconductivity induced by electron-phonon coupling[1].
In superconductors, superfluidity appears in the system with emergence of a well-definedmacroscopic phase, which originates from the macroscopic particle-number fluctuation. Although the existence of the macroscopic phase can be observed through the DC Josephson
eﬀect[2-4], the origin of the particle-number fluctuation is not clear in isolated systems. Recently, a variational wave function of superconductors has been constructed, which incorporate
the correlation eﬀects between Cooper pairs beyond BCS theory[5]. According to the study,
the correlations produce finite non-condensed particles in the ground state, consequently, thefluctuation of the number of Cooper pairs occurs naturally.
In this presentation, we construct the variational ground-state wave function of weakly interacting homogeneous fermion-boson mixtures with particle-number-conserving manner. Using
the ground state, we show the following topics. (1) The fermion-boson interaction induces
quantum depletion of the BEC. (2) The quantum depletions interact with fermions and giverise to the momentum-emission (-absorption) processes of fermions in the same way as electronphonon coupling. (3) The ground-state is given as a superposition over diﬀerent particle-numberof states even in the number-fixed systems. Therefore, superconducting state with well-definedmacroscopic phase may appear naturally even in the number-fixed fermions due to the fermionboson interactions. We also show the numerical results assuming the system is a dilute atomicgas. We discuss the nature of the ground state quantitatively by showing the results of groundstate energy, quantum depletions, and pair potential of fermions.
[1] J. Bardeen, L. N. Cooper, and J. R. Schrieﬀer, Phys. Rev. 106, 162 (1957).
[2] B. D. Josephson, Phys. Lett. 1, 251(1962)[3] V. Ambegaokar, and A. Baratoﬀ, Phys. Rev. Lett. 10, 486 (1963).
[4] P. W. Anderson, and J. M. Rowell, Phys. Rev. Lett. 10, 230 (1963).
[5] X. Si, WK, and T. Kita, submitting

24th, session 6, poster 3
Magnetization measurement of Ce(Ru1-xRhx)2Al10 (x < 0.05) under Electric
Current
Blank line (12 points)
N. Shikanai1, M. Yamamoto1, A. Kohriki1, H. Hidaka1, T. Yanagisawa1, H. Amitsuka1,
H. Saito2, C. Tabata3, H. Tanida4, T. Matsumura5, and M. Sera5
Blank line (12 points)
1

Graduate School of Science, Hokkaido Univ., Sapporo 060-0810, Japan
2
KENS IMSS KEK, Naka 319-1106, Japan
3
PF IMSS KEK, Tsukuba 305-0801, Japan
4
Liberal Arts and Sciences, Toyama Pref. Univ., Imizu 939-0398, Japan
5
ADSM, Hiroshima Univ., Higashihiroshima 739-8530, Japan

Blank line (12 points)
Toroidal moment t is one of the parameters that describe strength of the magnetoelectric
coupling. According to a theoretical prediction by S. Hayami et al., the toroidal moment can be
active even in metallic systems, where the occurrence of exotic phenomena, such as magnetizationinduced by electric current, is expected [1]. Recently, we experimentally found the electric currentinduced magnetization in an antiferromagnetic (AFM) ordered state of a metallic system UNi 4B [2].
However, the observed magnetoelectric effects in UNi4B cannot be explained in part by thetheoretical model. Further investigation in other metallic systems with the toroidal moment isrequired for full understanding of the magnetoelectric effect.
We now focus our attention on another AFM metallic system CeRu2Al10 and its Rh-doped
system Ce(Ru0.95Rh0.05)2Al10. They crystallize into YbFe2Al10-type orthorhombic structure with
Cmcm (D2h17, No. 63), where Ce ions align along c-axis forming zigzag structure, with no local
inversion symmetry. Magnetic moments of the Ce ions order antiferromagnetically pointing to thec-axis at TN = 27 K for CeRu2Al10, while the magnetic moments of Ce(Ru0.95Rh0.05)2Al10 point tothe a-axis with the AFM ordering below TN = 24 K [3,4]. Both AFM orders have same propagation
vector of q = (0, 1, 0). In the present study, dc M measurements under electric current for eachsetting of I || a and c, and H || a, b, and c have been performed using large single crystalline samples
provided by H. Tanida. Figure 1 shows the temperature dependence of M under I for CeRu2Al10. It
is found that the additional M (ΔM) is induced by applying electric current below TN for the threesettings: (I, H) || (a, c), (c, a), and (c, b). Similar ΔM are also observed in Ce(Ru0.95Rh0.05)2Al10. We
are going to discuss about the cause of the observed magnetoelectric effects in these compounds
based on the concept of odd-parity multipoles.

Fig. 1. Temperature dependence of M under electric current at H = 100 Oe for CeRu2Al10. (left) I || a, and H || a, b,
and c; (right) I || c, and H || a, b, and c.

References[1] S. Hayami, H. Kusunose, and Y. Motome, Phys. Rev. B 90, 024432 (2014).
[2] H. Saito, et al., J. Phys. Soc. Jpn. 87, 033702 (2018).
[3] H. Kato, et al., J. Phys. Soc. Jpn. 80, 073701 (2011).
[4] R. Kobayashi, K. Kaneko, and K. Saito, J. Phys. Soc. Jpn. 83, 104707 (2014).

24th, session 6, poster 4
Charge Redistribution in Dirty Type-II Superconductors Due to Impurity
Scatterings in the T-Matrix Approximation.
Muhammad Zafur1, Hikaru Ueki2, Takafumi Kita1
1. Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
2. Dept. of Mathematics and Physics, Hirosaki University, Hirosaki 036-8560, Japane-mail: zafur@phys.sci.hokudai.ac.jp

In dirty s-wave superconductors, alongside the Lorentz force and the pair-potential
gradient (PPG), there exists another source of charge redistribution originally from impurity
atom scatterings which are known to affect the magnetic properties of the materials [1][2][3].
In this work, we investigate the charge redistribution of an isolated vortex of s-wave
superconductors due to the impurity self-energy in the t-matrix approximation based on thequasiclassical equations for superconductivity [4] and compare its contributions to thecharging properties of s-wave superconductors in competition with the Lorentz and PPG
forces. Furthermore, we are able to do a numerical comparison between the Born
approximation and the more general t-matrix approximation in term of their responses totemperature and Matsubara frequency. The numerical calculations are done by treating theimpurity self-energy as a perturbation since its order is very small, hence we can carry out aperturbation expansion of the quasiclassical equations [5]. In contrast with those caused by
the Lorentz and PPG forces, we found that the impurity self-energy gives rise to a charge
redistribution in which negative charges are accumulated at the vortex center. For the caseof medium and strong impurity potential (Gn/D0 ³ 0.5 ), the magnitude of charge density due
to the impurity self-energy is always slightly larger than the one caused by the Lorentz force
and still much smaller than that of the pair-potential gradient. Moreover, maximum charge
density in the vortex core is obtained in the Born limit (d0 = 0), setting delta to certain value
leads to lower charge density. More details regarding results and methods will be presented
at the conference.

References[1] T. Kita, Statistical Mechanics of Superconductivity (Springer, Tokyo, 2015).
[2] H. Ueki, W. Kohno, and T. Kita, J. Phys. Soc. Jpn. 85, 064702 (2016).
[3] M. Ohuchi, H. Ueki, and T. Kita, J. Phys. Soc. Jpn. 86, 073702 (2017).
[4] T. Kita, Phys. Rev. B 64, 054503 (2001).
[5] T. Kita, Phys. Rev. B 79, 024521 (2009).

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24th, session 6, poster 6

Electronic Superstructures in High-Tc Cuprate Bi2 Sr2 CaCu2 O8+x :an STM/STS study
S. Mizuta1 , T. Kurosawa1 , N. Momono2 , H. Yoshida1 , M. Oda1 and M. Ido1
1

2

Department of Physics, Hokkaido University, Sapporo, Japan
Department of Applied Sciences, Muroran Institute of Technology, Muroran, Japan

In the present work, STM/STS measurements were carried out in the superconducting state ofunderdoped (UD) Bi2 Sr2 CaCu2 O8+x (Bi2212) crystals with a hole doping level of ∼0.12. We investigated the mutual relationship among three types of electronic superstructures such as checkerboard modulation (CBM) [1–4], Cu–O–Cu bond-centered modulation (BCM) [5, 6] and quasiparticle interference modulation (QPIM) [5, 7], by focusing on their spatial dependence.
The STS spectrum measured in the UD samples was well-understood in terms of two energy
gaps coexisting in the antinodal region; it exhibits broad peaks corresponding to the pseudogap(PG) at larger energies |E| = ∆PG and subgap (SG) behavior at smaller energies |E| = ∆PG ,which is comparable with the pairing gap size ∆pair (fig. 1(a)). CBM is found in images of thelocal density of states (LDOS) for energies around ∆SG , whereas BCM is found in those for energies
around ∆PG (figs. 1(b) and (c)). These two superstructures, which are characterized by energyindependent wavevectors or nondispersive, are formed in the same regimes within CuO2 planes.
This finding implies that the spatial structure of electronic states in the antinodal region seems tochange from CBM to BCM with increasing energy.
Furthermore, we confirmed that CBM coexists with QPIM, which is caused by the interferenceof Bogoliubov quasiparticles on the nodal Fermi arc hosting the d-wave superconducting gap. As iswell known, QPIM consists of seven independent components, and each of them is characterized byan energy-dependent wavevector. For one of the components, q1 -QPIM, the wavevector is similar
to that of the nondispersive CBM at energies around ∆SG , wherein we established a stimulating
relation, depending on the polarity of STM bias voltage Vs , between the phases of CBM andq1 -QPIM. In this conference, we will report the detailed features on their coexistence.
(b)dI / dV (a.u.)

(a)

(c)

∆PG
∆SG

-100 -50 0 50 100
Vs (mV)

2 nm

Cu–O
bond dir.

Figure 1: (a) Representative STS spectrum in UD-Bi2212. (b) LDOS images for Vs = ∆PG /e and (c) for+20 mV (∼ ∆SG /e). BCM and CBM are clearly observed in the boxed region in (b) and (c), respectively.
References[1]. C. Howald et al., Phys. Rev. B 67, 014533 (2003).
[2]. R. Comin et al., Annu. Rev. Condens. Matter Phys. 7, 369 (2016).
[3]. T. Kurosawa et al., J. Phys. Soc. Jpn. 85, 044709 (2016).
[4]. S. Mizutaet al., J. Phys.: Conf. Ser. 969, 012071 (2018).
[5]. Y. Kohsaka et al., Nature 454, 1072 (2008).
[6]. M. H. Hamidian et al., Nat. Phys. 12, 150 (2016).
[7]. K. Fujita et al., Science 344, 612 (2014).

24th, session 6, poster 7

Magnetic Properties of Perfect Kagome Lattices in YCu3 (OH)6 Cl3
T. Okada1 and H. Yoshida1
1Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan

Geometrically frustrated magnets have been investigated due to their nontrivial magnetic state, especiallythe quantum spin liquid (QSL) state. Herbertsmithite and kapellasite, ZnCu3 (OH)6 Cl2 , are the best known
S=1/2 quantum kagome (corner-sharing triangular) antiferromagnet and the realization of a QSL state has
been proven theoretically. In actual materials, however, their anti-site disordering between magnetic Cu2+ andnonmagnetic Zn2+ ions in the kagome plane hinders the ground state properties of the kagome compounds.
In order to avoid the anti-site disorder, many eﬀorts have been taken. We have succeessfully synthesized single
crystals of the S=1/2 kagome antiferromagnet CaCu3 (OH)6 Cl2 ·0.6H2 O [1]. This compound was expected forrealization of a novel magnetic state with spin fluctuation due to its strong frustration and quantum fluctuation
on kagome lattice. Sun et al. showed a possible QSL state in YCu3 (OH)6 Cl3 [2]. It crystallizes in the trigonal
symmetry with space group P-3m1 and has a perfect kagome lattice without any mixing between magnetic
Cu2+ and nonmagnetic Y3+ . They reported that no magnetic order down to 2 K was observed in magnetic
suscepribility.
We have succeeded in preparing single crystals of YCu3 (OH)6 Cl3 as shown in Fig. 1 (c) and have performed themagnetic susceptibility measurements. Figure 2 shows temperature dependences of the magnetic susceptibility
on polycrystalline YCu3 (OH)6 Cl3 . We found that antiferromagnetic ordering was suppressed below 100 K in
this compound.
In my presentation, I will show details of single crystal syntheses and discuss the magnetic properties ofperfect kagome antiferromagnet YCu3 (OH)6 Cl3 .
This study was supported by the Grant-in-Aid for Scientific Research C (18K03529).

Fig. 2: Temperature dependence of the magnetic susFig. 1: (a),(b) Crystal structure of YCu3 (OH)6 Cl3 (c) ceptibility on polycrystalline sample measured at 1000
The picture of single crystals obtained in this study.
Oe.

References[1] H. Yoshida, et al., Journal of the Physical Society of Japan 86, 033704 (2017)[2] W. Sun, Y. X. Huang, S. Nokhrin, Y. M. Pan and J. X. Mi, J. Mater. Chem. C, 2016, 4, 8772

24th, session 6, poster 8

13

C NMR of λ-(BEDT-TTF)2GaCl4 under pressure
Masashi Sawada

Low temperature physics group, Department of Condensed Matter Physics,
Graduate School of Science, Hokkaido University
1. Introduction
Figure 1 shows the universal P-T phase diagram of
λ-(D)2GaCl4 [D = ET (BEDT-TTF), STF, BETS]. λ(BETS)2GaCl4 salt shows a SC transition at 5 K.
Previous 13C NMR study has revealed that an AF spin
fluctuation exists before the SC transition [1]. Hence,

To reveal the nature of the magnetic property of λ(D)2GaCl4 in the intermediate pressure region, we
have performed 13C NMR under pressure for λ(ET)2GaCl4 which does not have an asymmetry in thedonor molecule.
2. Experiments
Single crystals of λ-(ET)2GaCl4 were synthesized byelectrochemical method. 13C NMR was performed
under magnetic field of 6 T and under pressure 2.5
kbar. The NiCrAl alloy clamp cell and Daphne 7474
oil were used for pressurizing. We have measured thespin-lattice relaxation time (T1) for 2-100 K.
3. Results and Discussion
Figure 2 shows the temperature dependence of the
1/T1T. Below 25 K, 1/T1T rapidly increases withdecreasing temperature and has a peak at 3 K. Thisbehavior indicates the AF transition occurs at 3 K and

Fig. 1 The universal P-T phase diagram of λ-(D)2GaCl4

AF phase is suppressed by applying pressure. Thisimplies that nonmagnetic phase of STF salt is not due
to the asymmetry of STF molecule, instead, it is an
intrinsic property.

10

1/T1T (s-1K-1)

it has been expected that the SC transition is driven by
AF spin fluctuation. However, the adjacent phase to
the SC phase is a nonmagnetic insulating phase.
Although λ-(ET)2GaCl4 shows an AF ordering below
13 K at ambient pressure [2], λ-(STF)2GaCl4 does notshow AF ordering down to lowest temperature. In
general, STF molecule has an asymmetricarrangement of S and Se atoms. Hence, it is possiblethat the asymmetry of STF molecule plays as a role ofdisorder and prevents an AF ordering in STF salt [2].

1

0.1

0

20

40

60

80

100

120

Temperature (K)Fig. 2 The temperature dependence of 1/T1T

4. Conclusion
We have performed 13C NMR for λ-(ET)2GaCl4
under pressure 2.5 kbar and confirmed that thetemperature dependence of 1/T1T has a peak at 3 K.
References[1] T. Kobayashi, doctor thesis (2018).
[2] Y. Saito et al. JPSJ 87, 013707 (2018).

24th, session 6, poster 9

Motivation for supersymmetry theory
Department of Physics, Hokkaido University
Yuta Mimura

Standard Model is verified by many experiments but has several unsolved problems.
Hierarchy problem is one of that. By introducing Supersymmetry we can solve it andalso can get some by-products such as giving a candidate for Dark Matter. In thissession, I explain mainly Hierarchy problem and how supersymmetry theory solves it,then refer to other beneficial predictions that are given by considering Supersymmetry.

24th, session 6, poster 10

Domain Wall
Seiya Yamada
Department of Physics, Hokkaido University

Abstract
In the early universe, the universe whose vacuum was considered tohave high symmetry had high density and high temperature. The temperature of the universe fell down due to the expansion of space. Then, it
is considered that phase transition had occured due to the spontaneous
symmetry breaking (SSB) and produced topological defects.
I am going to introduce a domain wall which is an example of a topological defect associated with SSB by using a simple scalar model. Considera Lagrangian of a real scalar field
L=

"2
1
1 !
2
(∂µ φ) − λ φ2 − σ 2 .
24The symmetry of the Lagrangian is spotaneously broken when scalar field
φ takes two vacuum expectation values (VEV). Then, space is divided
into two regions (φ = +σ, φ = −σ). A Domain wall that has energy
occurs at the boundary between the two regions.

We can estimate the surface energy density associated with the domain
wall. I will show the value of energy in this poster session.
Next, I will briefly explain Cosmic string which is one dimensional
topological defect. Since Cosmic string is closely related to cosmology,
cosmic string have been studied intensively.
References[1] Kolb, Edward W. and Turner, Michael S, ”The Early Universe”

24th, session 6, poster 11
Peculiar Magnetization Reversal of TbNiC2
M. Yamamoto1, H. Hidaka1, T. Yanagisawa1, C. Tabata2, H. Nakao2, S. Shimomura3,
H. Onodera4, and H. Amitsuka1
1

2

Dept. of Physics, Hokkaido Univ., Sapporo 060-0810, Japan
Condensed Matter Research Center and Photon Factory, Institute of Materials Structure Science, HighEnergy Accelerator Research Organization, Tsukuba 305-0801, Japan
3
Dept. of Physics, Kyoto Sangyo Univ., Kyoto 603-8555, Japan
4
Dept. of Physics, Graduate School of Science, Tohoku Univ., Sendai 980-8578, Japan

TbNiC2 has attracted much attention because of its rich and interesting properties of spin and chargeordering. It crystallizes in a noncentrosymmetric A-centered orthorhombic CeNiC2-type structurewith a space group Amm2 (C2v14, No. 38) [1]. The system exhibits a charge density wave (CDW)
order with an incommensurate propagation vector q1 of (0.5, K, 0) at 243 K and two successivecommensurate ones with q1C of (0.5, , 0) and q2 of (0.5, 0.5, 0.5) at 160 K and 128 K, respectively.
The commensurate CDW ordering state with q1C persists even when the system undergoes anantiferromagnetic (AFM) transition at TN = 25 K [2]. The reported magnetic structure is a noncollinear
type described by the same propagation vector as q1C with the Tb moments of 6.8 PB, where Tb
moments are canted by about 13°from the c axis and by about 7°from the b axis [3,4]. The abovementioned multiple phase transitions in TbNiC2 imply an intriguing interplay between CDW and
AFM [2]. Moreover, the system exhibits a weak spontaneous magnetization M of about 0.22 PB in
the AFM state [5]. Although the above-mentioned magnetic structure cannot explain this weakferromagnetic component, there are few studies in
low-magnetic fields thus far. We thus focus on the
0.9
magnetic response to low-magnetic fields in order to10000 Oe
TbNiC
1000 Oe
H || c (#1)
reveal the origin of the weak ferromagnetism of this
500 OeFC
300 Oe0.6
system.
100 OeIn the present study, the magnetization for the
0.3
single-crystalline samples of TbNiC2 along different
field directions were measured in the temperature
0.0
range from 2 to 300 K with applied magnetic field up
to 15 kOe. Figure 1 shows M as a function of-0.3
temperature upon field cooling (FC) in various
0
50
100
T(K)
magnetic fields along the c axis. We found that M in
the FC process decreases below TN across zero with Fig. 1. Temperature dependences of thedecreasing temperature, and becomes negative with magnetization upon FC in various magnetic fields
fields lower than 500 Oe. It is revealed that this along the c axis.
unusual “magnetization reversal” occurs only below
0.6
TbNiC
TN and only in the FC process. As can be seen in Fig.
H || c (#1)
0.4
FC (H = 100 Oe)
2, it is clear that the observed magnetization reversal
20K
10K
is not due to a conventional diamagnetism such as the
0.2
6K
core diamagnetism or Landau diamagnetism since
0.0
the differential susceptibility is always positive. We-0.2
will discuss the origin of this peculiar magnetization
reversal of TbNiC2.
-0.4
M ( B/Tb)

2

M ( B/Tb)2

0.3

M ( B/Tb)

0.2
0.1
0.0

-0.1
-0.2

-0.3
-3

References[1] W. Jeitschko et al., J. Less-Common Met. 116, 147 (1986).
[2] S. Shimomura et al., Phys. Rev. B 93, 165108 (2016).
[3] J.K. Yakinthos et al., J. Magn. Magn. Mater. 81, 163 (1989).
[4] N. Uchida et al., J. Magn. Magn. Mater. 145, L16 (1995).
[5] H. Onodera et al., J. Magn. Magn. Mater. 137, 35 (1994).

-0.6
-15

-2

-1

0

1

2

3

H (kOe)

-10

-5

0

5

10

15

H (kOe)Fig. 2. Isothermal magnetization processes
measured at several temperatures for magnetic
field along the c axis after FC at 100 Oe.

24th, session 6, poster 12

Electrical Properties of λ’-(BEDT-STF)2GaBr4 at High Pressures
Satoshi Kawaguchi, Takuma Wada, Takaaki Minamidate, Masashi Sawada, Noriaki Matsunaga, Atsushi
Kawamoto, Kazushige Nomura
Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
Email: kawaguchi-satoshi@eis.hokudai.ac.jp
A quasi-two-dimensional organic conductor λ-(BETS)2GaCl4 shows superconducting phase at 5.5 K atambient pressure.[1] Recently, we found that λ-(BEDT-STF)2 GaCl4 locates at lower pressure region thanthat of λ-(BETS)2GaCl4 and the phase adjacent to the SC phase in λ-type systems is not the antifferro
magnetic phase.[2] In contrast, λ’-(BETS)2GaBr4 shows the transition from a (semi)metallic state to theinsulating state at 50 K.[3] To clarify the origin of MI transition and the difference from the λ-type salt,
we performed the resistivity measurements under pressure, magnetic susceptibility measurements atambient pressure and NMR measurements.
Single crystals of new material λ’-(BEDT-STF)2GaBr4 were synthesized by the standard
electrochemical method. Gold wires were attached to the crystal with carbon paste as electrodes. The
crystal was mounted inside a BeCu and NiCrAl hybrid cramp cell with Daphne 7373 oil as a pressure
medium. We measured the resistivity under pressure and the magnetic susceptibilities at ambient pressureof λ’-(BEDT-STF)2GaBr4. λ’-(BEDT-STF)2GaBr4 shows insulating state in whole temperature region.
This insulating behavior was gradually suppressed with increasing pressure. The transition temperature
decrease with increasing pressure. This transition is thought to be correspond to the transition to theinsulator phase which observed in λ’-(BETS)2GaBr4 around 50 K at ambient pressure. We concluded thatλ’-(BEDT-STF)2GaBr4 locates at the lower pressure region than that of λ’-(BETS)2GaBr4 in the universal
phase diagram and the insulator phase appears in the wide pressure region. The magnetic susceptibility atambient pressure decreased rapidly below 50 K. Subtracting the Curie component, the core diamagnetismand the contribution of stycast, the magnetic susceptibility approached to zero. So λ’-(BEDT-STF)2GaBr4
is thought to show the transition to non-magnetic state. NMR spectra of the λ’-(BEDT-STF)2GaBr4 at
ambient pressure does not show temperature dependence. The spin-lattice relaxation rate 1/T1 drasticallydecreases at 50K and slowly decreases below 50 K. The decrease of 1/T1 is consistent with the transitionof magnetic susceptibility. However this non-magnetic state is not simple spin-Peierls state because 1/T1
gradually decreases below 50 K.
-0.0005
0.3T
0.5T
0.7T
1T
3T
5T
7T

3

1/T1 (s-1)χ (emu/m ol)-0.0006

4-0.00072

1-0.0008

0

50

100

Temperature (K)Fig. 1. Magnetic susceptibility at ambientpressure of λ’-(BEDT-STF)2GaBr4
References[1] H. Kobayashi, et al, Chem. Lett., 22, 1559 (1993)[2] T. Minamidate, et al, JPSJ, 84, 063704 (2015)[3] H.Tanaka, et al, Chem. Lett., 28, 133, (1999)

0
0

20

40

60

80

100

Temperature (K)Fig. 2. 1/T1 at ambient pressure of λ’-(BEDTSTF)2GaBr4

24th, session 6, poster 13
Electronic Properties in SDW Phase of
Quasi-One-Dimensional Organic Conductor (DMET-TTF)2AuBr2
Yoshiaki Sasaki, Tomoaki Tsuchiya, Noriaki Matsunaga, Atsushi Kawamoto, and Kazushige Nomura
Department of Physics, Hokkaido University
Email: ysasaki_epldc@eis.hokudai.ac.jp
The DMET-TTF, where DMET-TTF dimethyl(ethylenedithio)tetrathiafulvalen, molecular is a hybrid
structure between TMTTF and BEDT-TTF. In a similar substance (DMET)2X (X is a linear monovalentanion), where DMET is dimethyl(ethylenedithio)diselenadithiofuluvalen, donor molecules stack to form
columns along the b-axis, and this salt has a quasi-one-dimensional Fermi surface[1]. For example,(DMET)2Au(Cn)2 undergoes metal-SDW transition around 20 K at ambient pressure and superconducting
transition at 0.15 GPa[1]. (DMET-TTF)2AuBr2 determined by X-ray diffraction is isostructural compoundwith (DMET)2X (X is CuCl2[1] and Au(CN)2[2]), so this salt has quasi-one-dimensional Fermi surface.
We have investigated pressure dependence of electric properties of (DMET-TTF)2AuBr2. Figure 1
shows the temperature dependence of resistance and figure 2 shows the phase diagram of (DMETTTF)2AuBr2. At 0.3GPa, metallic state was observed at high temperature, and metal-insulator transition
was observed at 38.8 K and 16.8 K for 0.3 GPa and 0.6 GPa, respectively. The M-I transition temperature
decreases with increasing pressure. The superconducting transition was also observed at 3.38 K under
0.85 GPa. The resistance was well described by thermally activation type in insulator phase. From theanalogy with phase diagram of (DMET)2Au(CN)2[3], the M-I transition has been considered SDWtransition. In SDW phase, the definite threshold electric field and increase of SDW transition temperature
TSDW with increasing magnetic field were observed. In particular, we have focused on the SDW sliding,and performed non-linear conduction measurements at various temperature.

Fig. 1. The temperature dependence of resistanceunder 0.3GPa and 0.6GPa.
References[1]H. Ito et al., PRB, 71, 212503 (2005)[2]K. Kanoda et al., PRB, 38,39 (1988).
[3]H. Yoshino et al., JPSJ, 64, 2307 (1995)

Fig. 2. The phase diagram of (DMET-TTF)2AuBr2.

24th, session 6, poster 14

Ultrasonic Study of Quadrupolar Response in CeTe under Hydrostatic Pressure
T. SAITO1, H. MATSUMORI1, H. HIDAKA1, T. YANAGISAWA1, H. AMITSUKA1, Y.
HAYASHI2, T. MATSUMURA2, S. NAKAMURA3 and A. OCHIAI4
1
Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan 2
Department of Quantum Matter, AdSM, Hiroshima University, Higashi-hiroshima, Hiroshima 739-8530, Japan
3
Institute for Materials Reserchment, Tohoku University, Sendai 980-8577, Japan
4
Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan

2

A Kondo compound CeTe has NaCl-type cubic structure (Fm3m, Oh5, No. 225), where the CEF (crystalline
electrical field) ground state of J = 5/2 multiplet splits into Γ 7 doublet and Γ 8 quartet. This material has
previously been considered as a simple antiferromagnet [1]. Recent studies of electrical resistivity,
Magnetization and specific heat under hydrostatic pressure, however, reveal that the CEF levels of thesesystems are getting degenerated by applying pressure and antiferroquadrupolar (AFQ) phase will be appeared
under applied magnetic fields or applying pressure above 1 GPa [2]. In the present study, we investigated elastic
constant C44 of CeTe by means of ultrasound under hydrostatic pressure P < 2.45 GPa. For the hydrostaticpressure measurements, a new technique has been developed and used for the present experiments, which has
allowed high-frequency ultrasonic measurements under pressure by installing a pair of ultra-thin semi-rigid
coaxial cables with a diameter of 0.33 mm into a hybrid piston-cylinder cell. [3] Figure 1(a) shows temperaturedependences of the elastic constant C44 of CeTe at P = 2.45 GPa. The C44 decreases with decreasing temperatureand shows several anomalies below about 6 K. Figure 1(b) shows the magnetic field dependences of the elastic
constant C44 of CeTe. Figure 1(c) shows the temperature-magnetic field phase diagram of CeTe defined byanomalies of temperature dependence and magnetic field dependence. Phase IV is assumed AFQ phase by
resent study [2]. I-IV phase line consistent with resent phase diagram by magnetization and specific heat. Phase
V and dot lines are found newly by elastic constants. Based on investigation of the hydrostatic pressure variationof the elastic constant, we can obtain additional information regarding the hybridization between conduction
electron and f-electron, c-f hybridization, and its consequences on the modification of the CEF level scheme
change under pressure.
(b)

(a)

(c)

TQ’

V

TQ
TQ

TN

IV

TQ’

TN

II

I

Fig. 1: Temperature Dependence(a) and Magnetic Field Dependence(b) of Elastic Constant C44 of
CeTe at P = 2.45 GPa and Temperature-Magnetic Field Phase Diagram(c)[1] H. Matsui, T. Goto, A. Tamaki, T. Fujimura, T. Suzuki, and T. Kasuya, J. Mag. Mag. Mat. 76&77 (1988) 321.
[2] H. Takaguchi, Y. Hayashi, T. Matsumura, K. Umeo, M. Sera, and A. Ochiai, J. Phys. Soc. Jpn. 84 (2015) 044708.
[3] S. Mombetsu, T. Murazumi, H. Hidaka, T. Yanagisawa, H. Amitsuka, P.-C. Ho, and M. B. Maple, Phys. Rev. B 94 (2016)085142.

24th, session 6, poster 15

Superconductivity in Cu-doped TaSe3: Relationship between
superconductivity and induced charge density wave
Atsushi Nomura,1 Kazuhiko Yamaya,2 Shigeru Takayanagi,2 Koich Ichimura,1, 2
and Satoshi Tanda1, 2
1
Department of Applied Physics, Hokkaido University
2
Center of Education and Research for Topological Science and Technology,
Hokkaido University
The relationship between superconductivity (SC) and charge density wave (CDW)
has been a major research topic in condensed matter physics and has been
investigated in many materials. However, previous studies were actually limited totwo cases: the first is where SC and a CDW intrinsically coexist in a material; thesecond is where SC is induced in a CDW material. Here, in addition to these twocases, we should also investigate the relationship in a third case where a CDW is
induced in a superconducting material, if we are to gain a universal understanding.
Recently, we reported that the CDW transition is induced by Cu doping in TaSe3
which is a superconducting material [1]. Therefore, in this study, we investigated SC
in Cu-doped TaSe3 by measuring the temperature dependence of the resistance toclarify the effect of Cu doping on SC and the relationship between SC and an
induced CDW.
We observed an emergence of a region where the SC transition temperature
decreases in samples with higher Cu concentrations and found that the region tended
to expand with increasing Cu concentration. In addition, the temperature dependenceof the upper critical field of Cu-doped TaSe3 was found to differ from that of pure
TaSe3. Based on these experimental results and the fact that the SC of TaSe3 isfilamentary, we conclude that SC is suppressed locally by Cu doping and competes
with the CDW in Cu-doped TaSe3. The resistance anomaly due to the CDW
transition was extremely small and the size of the anomaly was enhanced withincreasing Cu concentration but the temperature at which the anomaly appeared
hardly changed. This result of the anomaly and the local suppression of SC imply
that the induced CDWs are short-range order in the vicinity of Cu atoms.
[1] A. Nomura, K. Yamaya, S. Takayanagi, K. Ichimura, T. Matsuura, and S. Tanda, EPL 119,
17005 (2017).

24th, session 6, poster 16

Various physical properties of VO2 film by controlling deposition temperature
Yesul Choi1,3, Dooyong Lee1,3, Ji Woong Kim1, Sehwan Song1, Jong-Seong Bae2, Jaekwang Lee1and Sungkyun Park1,*
1

Department of Physics, Pusan National University, Busan 46241, Korea
2

3

Busan Center, Korea Basic Science Institute, Busan 46742, Korea

Advanced Nano Surface Research Group, Korea Basic Science Institute, Daejeon 34133, Korea

Abstract
Vanadium dioxide (VO2) shows an insulator-metal transition (IMT) at 68 oC. There are several
explanations of the IMT mechanism, such as the Peierls transition (i.e., structural transition), the Mott
transition (i.e., electronic transition) or collaborative Mott-Peierls transition. In this study, VO2 films
grown on Al2O3(001) substrate were deposited at various temperatures (e.g., 500 oC ~ 720 oC) toexamine the correlation effect between the vanadium multivalent (V3+, V4+, V5+) and structuralproperties, and IMT characteristics systematically. As a result, the IMT temperature and the resistivity
ratio (ρ(26 oC)/ ρ(100 oC)) are the greatest for the films deposited at 600 oC and 650 oC owing to thechange of V5+ to V4+ and the out-of-plane strain relaxation. On the other hand, for the films deposited
above 650 oC, the transition temperature and resistivity ratio sharply decreased owing to the increase inV3+ state (i.e., additional electrons), which reduced the thermal energy barrier for IMT. These results
provide the experimental evidence for a specific mechanism for IMT transition in separately.
This study was supported in part by NRF Korea (NRF-2015R1D1A1A01058672 and NRF2018R1D1A1B07045663).

*

Correspondence should be addressed to Sungkyun Park (psk@pusan.ac.kr)

24th, session 6, poster 17
Thickness Dependent Magnetic Properties of FeRh/MgO films
Sehwan Song, Jiwoong Kim, Dooyong Lee, Sungkyun Park*
Department of Physics, Pusan National University, Korea

FeRh shows meta-magnetic first-order phase transition above 350 K accompanied with isotropic lattice expansion
and variation of the magnetoresistance. These are great interests for future applications such as, heat assisted
magnetic random access memories (HAMRAM), magnetic cooling and spintronic devices [1, 2]. In particular, film formof FeRh showed modified magnetic properties owing to the presence of interface (bottom and/or top). For example,
the formation of ferromagnetic (FM) domain nucleation at the interface owing to the interfacial strain and chemical
diffusion of Fe or Rh can easily modify the antiferromagnetic (AFM) characteristics below transition temperature of
the films [3, 4]. Therefore, it is important to understand the role of interface of films and gain the physical insights.
In this study, we investigated the structural, chemical and magnetic properties FeRh/MgO(100) films by varying
deposition time (1, 2, 5, 10 min). Interestingly, the phase transition temperature increased and magnetization at AFM
region decreased as deposition time increased. The detailed structural and chemical analysis were performed to obtain
possible correlation between local structural ordering and physical property variations.
[1] S. Yuasa et al., J. Appl. Phys. 83, 6813 (1998).
[2] Y. Liu et al., Nat. Commun. 7, 11614 (2016).
[3] C. Gatel et al., Nat. Commun. 8, 15703 (2017).
[4] R. Fan et al., Phys. Rev. B 82, 184418 (2010).

This research is supported in part by NRF Korea (NRF-2015R1D1A1A01058672 and NRF-2017K1A3A7A09016305).

*

E-mail: psk@pusan.ac.kr

24th, session 6, poster 18
Finite Size Effects in La2CuO4 Nanoparticles Probed by µSR and NMR
S. Winarsih1,2, F. Budiman3, H. Tanaka3, T. Goto4, T. Adachi4, B. Kurniawan2,
I. Watanabe1,2
1

Meson Science Laboratory, RIKEN, Wako 351-0198, Japan
Department of Physics, Universitas Indonesia, Depok 16424, Indonesia
3
Department of Human Intelligence Systems, Kyushu Institute of Technology, Kitakyushu 8080196, Japan
4
Department of Engineering and Applied Sciences, Sophia University, Tokyo 102-8554,
Japan
2

Finite size effects, which refer to the reduction in particle size until they become nanoscale
sized, will introduce novel phenomena in magnetic materials [1-3]. For instance, Zheng et al.
reported that by reducing CuO particles down to ~5 nm, the Néel temperature, TN, wasdrastically decreased to 30 K, compared with bulk CuO which has TN=229 K [3]. We examinedsuch kind of nano-sized effects in the typical Mott insulator La2CuO4 (LCO) by using muon
spin relaxation (µSR) and NMR methods. Fig. 1 shows that muon spin precession started to beobserved around 35 K in LCO with particle size of 69 nm. It means long-range magnetic
ordering appear at much lower temperature than that observed in bulk LCO (~300 K). However,muon spin precession in nanoparticle case was strongly damped compared with bulk one. The
saturated internal field at the muon sites was determined to be about 420 G. This value wasalmost the same as that observed in bulk LCO. It is implied that the average magnetic momentof bulk LCO and nano-LCO are same but magnetic interaction might be changed due to nanosized effect. The 139La-NMR results also show that internal field has started to appear aroundthe same temperature as that estimated from µSR under zero-field (ZF) condition. µSR andNMR results of LCO nanoparticles and possible reasons of the reduction in TN in nano-sized
LCO will be presented.

Fig. 1: ZF-µSR of La2CuO4 with a particle size of 69 nm measured at various temperatures. Solidlines are the best-fit results assuming the single cosine function to reproduce the muon-spin precession
behavior.

References[1] A. Punnoose et al., Phys. Rev. B 64, 174420 (2001).
[2] Y. J. Tang et al., Phys. Rev. B 67, 054408 (2003).
[3] X. G. Zheng et al., Phys. Rev. B 72, 014464 (2005).

24th, session 6, poster 19

TBA24th, session 6, poster 20
μSR Studies on Electron Motion Along DNA Molecule*H. Rozak1,2), W.N. Zaharim2), S.N. Abu Bakar2), N.Ismail2),F. Astuti1,3), M.I. Mohamed-Ibrahim 2),S. Sulaiman2) and I. Watanabe1,2,3).
1)

RIKEN Nishina Center, 2) Universiti Sains Malaysia ,3) Hokkaido University

Deoxyribonucleic acid (DNA) is known as biological molecule that containing the genetic code for all
living species. The structure of DNA is consisting of four nitrogenous bases; adenine(A), guanine(G),cytosine(C) and thymine(T) attached to a sugar and phosphate group and arranged in base-pairs in a double
helix structure. One of the unique feature of DNA is the π-π interactions of the stacked base-pairs which
could lead to the conducting behavior of electron transport. Electron transport studies in DNA is important
not only for understanding the DNA damage and repair mechanisms, but also for possible applications as
bio-devices. From previous studies, two mechanisms of electron transport have been proposed, namely thetunneling and hopping mechanisms [1]. In order to study the electron transport phenomena, we have carriedout µSR measurement on the 12-mer single strands (A, G, C and T) molecule at 100 K and 300 K. Figure
1 (a) shows μSR time spectra from one of those models which is a 12-mer adenine at 300K, withlongitudinal magnetic fields up to 4000 G. As can be seen in Figure 1, the muon-spin relaxation behavior
is faster at ZF and at higher LF the relaxation behavior however not completely suppressed. This indicatesthat the muon feels strongly fluctuating internal fields. This is clearly shows that electrons are moving along
the single strand molecule and as well as generating fluctuating internal fields that influence the muon.
Figure 1(b) shows the applied field dependence of the muon-spin relaxation rate. This behaviour of thegraph reflects the dimensionality of the electron motion. From the previous studies 1 D diffusion behavior
observed the relaxation rate ∝ LF-0.5 [2], the result of our experiment however does not show clear 1 D
diffusion because λ(B) is not approximated to be proportional B-0.5. This might be due to geometricalstructure of the the single strand DNA molecule that does not form an ideal 1 D structure. Currently
scanning tunnelling microscope measurement being performed to determine the molecular structure of
DNA samples.
a)

b)
0.1

λ (µs-1)

B-0.27
Adenine 300K
0.01

0.001

100

1000

Longitudinal Field (G)Figure 1. (a) μSR time spectra of the single strand DNA adenine. (b) The applied magnetic-fielddependence of the muon-spin relaxation rate for 12-mer adenine measured at 300 K.
References
1. Boon, E. M., & Barton, J. K. (2002). Charge transport in DNA. Current opinion in structural
biology, 12(3), 320-329.
2. Butler, M. A., Walker, L. R., & Soos, Z. G. (1976). Dimensionality of spin fluctuations in highly
anisotropic TCNQ salts. The Journal of Chemical Physics, 64(9), 3592-3601.