Oral Session B2 (Wednesday, February 14)
Chair: Shinsei Ryu, Princeton University

Contributed Oral
11: 00 - 11 : 20

Ferroic multipole order in the quadrupole Kondo lattice
PrV2Al20 studied by magnetostriction and thermalexpansion
A. Sakai1 M. Fu1, T. Isomae1, M. Tsujimoto2, Y. Nagaoka2, N. Sogabe2 and S. Nakatsuji1-4
1. Department of Physics, The University of Tokyo, Japan
2. Institute for Solid State Physics, The University of Tokyo, Japan
3. Institute for Quantum Matter, Johns Hopkins University, USA
4. Trans-scale Quantum Science Institute, University of Tokyo, Tokyo, Japan
Strongly hybridized quadrupole system may induce anomalous metallic state through the two channel Kondo
eﬀect [1]. A cubic Pr-based rare-earth compound PrV2Al20 can provide such quadrupole Kondo system wherestrong c-f hybridization and quadrupole active nonmagnetic crystalline electric field ground state (cubic Γ3) are
realized. Besides, PrV2Al20 exhibits anomalous metallic behavior, multiple multipole orders at T ~ 0.75 and ~0.65
K, and superconductivity at Tc ~ 0.05 K [2, 3]. In this presentation, we will present our recent study for themultipole order of PrV2Al20 via magnetostriction and thermal expansion.

References[1] D. L. Cox, Phys. Rev. Lett., 59, 1240 (1987).
[2] A. Sakai and S. Nakatsuji, J. Phys. Soc. Jpn., 80, 063701 (2011).
[3] M. Tsujimoto et al., Phys. Rev. Lett. 113, 267001 (2014).

11: 20- 11 : 40

Versatile magnetic hedgehog lattice phases induced byanisotropic interactions in centrosymmetric systems
S. Okumura1 S. Hayami2, Y. Kato1, and Y. Motome1
1. The University of Tokyo, Japan
2. Hokkaido University, Japan

Oral Session B2 (Wednesday, February 14)
Chair: Shinsei Ryu, Princeton University

Recently, a new generation of topological spin textures has been discovered in centrosymmetric metals, where theDzyaloshinskii-Moriya interaction is absent. For instance, a three-dimensional topological spin texture composed offour spin helices, called the quadruple-Q hedgehog lattice (4Q-HL), was observed in the simple cubic perovskite
SrFeO3 [1]. While the 4Q-HLs have been studied theoretically by using eﬀective spin models reflecting
the itinerant nature of electrons [2, 3], the origin of the experimentally observed topological Hall eﬀect has not beenclarified.
In this work, we investigate the eﬀects of the Q-dependent anisotropic interactions on the 4Q-HL, which originate
from the spin-orbit coupling for the itinerant electrons in the centrosymmetric systems. By using simulated
annealing for the eﬀective spin model, we find that the anisotropic interactions modify the ellipticity of thecomposed spin helices and result in the other types of the 4Q-HL with four spin sinusoidal waves hosting a larger
number of hedgehogs and antihedgehogs than the isotropic case [3] [Figure 1(a)]. Furthermore, in an external
magnetic field, we find that the anisotropic interactions induce nonzero scalar spin chirality not only in the 4Q-HLstates but also in topologically trivial phases [Figure 1(b)].
References[1] S. Ishiwata et al., Phys. Rev. B 84, 054427 (2011); Phys. Rev. B 101, 134406 (2020).
[2] S. Okumura, S. Hayami, Y. Kato, and Y. Motome, Phys. Rev. B 101, 144416 (2020).
[3] S. Okumura, S. Hayami, Y. Kato, and Y. Motome, J. Phys. Soc. Jpn. 91, 093702 (2022).

Oral Session B2 (Wednesday, February 14)
Chair: Shinsei Ryu, Princeton University

Contributed Oral
11: 40 - 12 : 00

Emergent inductance from spin fluctuations in strongly
correlated magnets
Taekoo Oh1, and Naoto Nagaosa1
1. RIKEN CEMS, Japan
Recently, the intriguing phenomenon of emergent inductance has been theoretically proposed and experimentallyobserved in nanoscale spiral spin systems subjected to oscillating currents. Building upon these recent
developments, we put forward the concept of emergent inductance in strongly correlated magnets in the normal
state with spin fluctuations. It is argued that the inductance shows a positive peak at temperatures above theordering temperature. As for the frequency dependence, in systems featuring a single-band structure or a gapped
multi-band, we observe a Drude-type, while in gapless multi-band systems, a non-Drude inductance with a sharp
dip near zero frequency. These results oﬀer valuable insights into the behavior of strongly correlated magnets andopen up new possibilities for harnessing emergent inductance in practical applications.

References[1] arxiv:2308.06073.

12: 00 - 12 : 20

Majorana-mediated spin transport in the Kitaev model atfinite temperatures
H. Taguchi1, Y. Murakami2 and A. Koga1
1. Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 Japan
2. Center for Emergent Matter Science, RIKEN, Wako 351-0198, Japan
Spin transport mediated by Majorana fermions is one of the interesting phenomena realized in the Kitaev model[1], where spin excitations flow in the quantum spin liquid (QSL) region without the oscillations in spin moments[2]. This nontrivial phenomenon originates from the fact that the S=1/2 spins are fractionalized into the itinerant
and localized Majorana fermions in the Kitaev system. It is known that these Majorana fermions have distinct
energy scales, leading to the double peaks in the specific heat [3]. Therefore, it is unclear how stable theMajorana-mediated spin transport in the Kitaev model is against thermal fluctuations.

Oral Session B2 (Wednesday, February 14)
Chair: Shinsei Ryu, Princeton University

In this study, we examine finite-temperature spin dynamics in the Kitaev model by means of the thermal purequantum state method [4]. At low temperatures, the spin excitation propagates in a similar way to that for theground state. At intermediate temperatures, larger oscillations in the spin moments are induced in the otheredge, compared to the results at the ground state. At higher temperatures, excited localized Majorana fermions
disturb the coherent motion of the itinerant Majorana fermions, which suppresses the spin propagation. Our
results demonstrate an important role of thermal fluctuations in the Majorana-mediated spin transport [5].
References[1] A. Kitaev, Ann. Phys. 321, 2 (2006).
[2] T. Minakawa, Y. Murakami, A. Koga, and J. Nasu, Phys. Rev. Lett. 125, 047204 (2020).
[3] J. Nasu, M. Udagawa, and Y. Motome, Phys. Rev. B 92, 115122 (2015). [4] S. Sugiura,

12: 20 - 12 : 40

Field control of quasiparticle decay in a quantum
antiferromagnet
S. Hasegawa1, H. Kikuichi1, S. Asai1, Z. Wei1, B. Winn2, G. Sala2, S. Itoh3, andT. Masuda1, 3, 4
1. Institute for Solid State Physics, The University of Tokyo, Chiba 277-8581, Japan
2. Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
3. Institute of Materials Structure Science, High Energy Accelerator Research Organization, Ibaraki 305-0801,
Japan
4. Trans-scale Quantum Science Institute, The University of Tokyo, Tokyo 113-0033, Japan
Dynamics in a quantum material is described by quantized collective motion: a quasiparticle. The
single-quasiparticle description is useful for a basic understanding of the system, whereas a phenomenon beyond
the simple description such as quasiparticle decay which aﬀects the current carried by the quasiparticle is an
intriguing topic. The instability of the quasiparticle is phenomenologically determined by the magnitude of therepulsive interaction between a single quasiparticle and the two-quasiparticle continuum. Although thephenomenon has been studied in several materials, thermodynamic tuning of the quasiparticle decay in a single
material has not yet been investigated. Here we show, by using neutron scattering, magnetic field control of themagnon decay in a quantum antiferromagnet RbFeCl3, where the interaction between the magnon andcontinuum is tuned by the field [1]. At low fields where the interaction is small, the single magnon decay process isobserved. In contrast, at high fields where the interaction exceeds a critical magnitude, the magnon is pushed
downwards in energy and its lifetime increases. Our study demonstrates that field control of quasiparticle decay ispossible in the system where the two-quasiparticle continuum covers wide momentum-energy space, and thephenomenon of the magnon avoiding decay is ubiquitous.

Oral Session B2 (Wednesday, February 14)
Chair: Shinsei Ryu, Princeton University

References[1] S. Hasegawa et al., Nature Communications (in press).