Chiral gauge field in fully spin-polarized magnetic Weyl semimetal with magnetic domain walls

Ozawa, Akihiro*; Araki, Yasufumi; Nomura, Kentaro*

Journal of the Physical Society of Japan, 93(9), p.094704_1 - 094704_9, 2024/09

https://doi.org/10.7566/JPSJ.93.094704

Modulation of magnetization in magnetic Weyl semimetals leads to the shift of Weyl points in momentum space, which effectively serves as the chirality-dependent gauge field for the Weyl fermions. Here, we theoretically study such a magnetization-induced chiral gauge field, in a fully spin-polarized Weyl ferromagnet CoSnS. From a tight-binding model of CoSnS on stacked kagome lattice with magnetism, we calculate the magnetization-dependent evolution of the Weyl points in momentum space, resulting in the chiral gauge field. In the presence of the magnetic domain wall structure, we evaluate the chiral magnetic field arising from the spatial profile of the chiral gauge field. We find that a magnetic domain wall in CoSnS gives rise to a giant chiral magnetic field for the Weyl fermions, which reaches the order of a few hundred tesla to induce the Landau quantization. Such a giant chiral magnetic field may also influence the novel transport phenomena, such as the charge pumping by the domain wall motion, compatible with the spinmotive force.

Octupolar edge state in an orbital system on a square lattice

Kubo, Katsunori

Physical Review B, 110(7), p.075110_1 - 075110_7, 2024/08

https://doi.org/10.1103/PhysRevB.110.075110

Elastic and inelastic neutron scattering experiments under high pressure in the frustrated antiferromagnet CuFeO

Terada, Noriki*; Khalyavin, D. D.*; Manuel, P.*; Asai, Shinichiro*; Masuda, Takatsugu*; Saito, Hiraku*; Nakajima, Taro*; Osakabe, Toyotaka

Physical Review B, 110(2), p.024406_1 - 024406_9, 2024/07

https://doi.org/10.1103/PhysRevB.110.024406

The frustrated antiferromagnet CuFeO exhibits pressure-induced complex magnetic phase transitions from the commensurate collinear (CM1) phase to several incommensurate noncollinear phases. To study the effect of high pressure on magnetic interactions, we performed neutron diffraction and inelastic neutron scattering experiments under high-pressure conditions. With increasing pressure, the CM1 ground state becomes less stable against application of a magnetic field even below the critical pressure ( 3 GPa), as proved by the significant reduction in the critical magnetic field from =7.5 T to 4.5 T at 2.1 GPa. Additionally, the energy gap in the spin-wave dispersion relation is reduced from 1.0 to 0.88 meV by the application of a pressure of = 2.1 GPa. Comparing the experimental results with spin-wave calculations revealed that the change in the spin-wave excitation can be explained by the reduction in either the uniaxial anisotropy term or the degree of separation in the nearest-neighbor exchange interactions.

Difference in peripherality of the inclusive and reactions and its implications for a phenomenological reaction model

Nakada, Hibiki*; Nakayama, Shinsuke; Yoshida, Kazuki; Watanabe, Yukinobu*; Ogata, Kazuyuki*

Physical Review C, 110(1), p.014616_1 - 014616_8, 2024/07

https://doi.org/10.1103/PhysRevC.110.014616

Previous studies have revealed the importance of introducing surface correction into a phenomenological model for inclusive and reactions, and these findings have contributed significantly to the improvement of nuclear data evaluation. However, the necessity for the surface correction in an inclusive reaction has hardly been investigated.The energy spectra and their radial distributions for the and reactions are calculated by the one-step semiclassical distorted wave model.The radial distribution of the energy spectra for the reaction is shifted toward the outer region of the nucleus compared to the reaction. Based on this finding, we consider a larger surface correction into a phenomenological model for the reaction than that for the reaction, and calculated values reproduce the experimental spectra well.The peripherality of the reaction is more prominent than that of the reaction. The stronger surface correction thus should be introduced for the reaction than for the reaction.

Dual chiral density wave induced oscillating Casimir effect

Fujii, Daisuke; Nakayama, Katsumasa*; Suzuki, Kei

Physical Review D, 110(1), p.014039_1 - 014039_15, 2024/07

https://doi.org/10.1103/PhysRevD.110.014039

The Casimir effect is known to be induced from photon fields confined by a small volume, and also its fermionic counterpart has been predicted in a wide range of quantum systems. Here, we investigate what types of Casimir effects can occur from quark fields in dense and thin quark matter. In particular, in the dual chiral density wave, which is a possible ground state of dense quark matter, we find that the Casimir energy oscillates as a function of the thickness of matter. This oscillating Casimir effect is regarded as an analog of that in Weyl semimetals and is attributed to the Weyl points in the momentum space of quark fields. In addition, we show that an oscillation is also induced from the quark Fermi sea, and the total Casimir energy is composed of multiple oscillations.

Spin and lattice dynamics in the van der Waals antiferromagnet MnPSe

Liao, J.*; Huang, Z.*; Shangguan, Y.*; Zhang, B.*; Cheng, S.*; Xu, H.*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Bao, S.*; Wen, J.*

Physical Review B, 109(22), p.224411_1 - 224411_10, 2024/06

https://doi.org/10.1103/PhysRevB.109.224411

Three-dimensional electrical resistivity structure beneath a strain concentration area in the back-arc side of the northeastern Japan Arc

Usui, Yoshiya*; Uyeshima, Makoto*; Hase, Hideaki*; Ichihara, Hiroshi*; Aizawa, Koki*; Koyama, Takao*; Sakanaka, Shinya*; Ogawa, Tsutomu*; Yamaya, Yusuke*; Nishitani, Tadashi*; et al.

Journal of Geophysical Research; Solid Earth, 129(5), p.e2023JB028522_1 - e2023JB028522_22, 2024/05

https://doi.org/10.1029/2023JB028522

We elucidated the crustal heterogeneities beneath a strain concentration area on the back-arc side of the northeastern Japan Arc based on electrical resistivity. By deploying magnetotelluric surveys, we revealed the three-dimensional electrical resistivity structure in the crust, suggesting the coexistence of two types of strain-concentration mechanisms in the strain-concentration area. The shallow conductive layers and lower-crustal conductors appear to act as low-elastic-modulus and low-viscosity areas, respectively, and are responsible for the strain concentration. We found a spatial correlation between the edges of the lower-crustal conductors and the epicenters of large intraplate earthquakes. Weak shear zones in the conductive lower crust may cause stress loading on faults in the brittle upper crust, resulting in large earthquakes. We also identified vertical conductors ranging from the lower crust to Quaternary volcanoes, which may indicate fluid paths to these volcanoes.

Single helicity of the triple- triangular skyrmion lattice state in the cubic chiral helimagnet EuPtSi

Matsumura, Takeshi*; Tabata, Chihiro; Kaneko, Koji; Nakao, Hironori*; Kakihana, Masashi*; Hedo, Masato*; Nakama, Takao*; Onuki, Yoshichika*

Physical Review B, 109(17), p.174437_1 - 174437_8, 2024/05

https://doi.org/10.1103/PhysRevB.109.174437

Comprehensive estimation of nuclide production cross sections using a phenomenological approach

Iwamoto, Hiroki; Meigo, Shinichiro; Sugihara, Kenta*

Physical Review C, 109(5), p.054610_1 - 054610_12, 2024/05

https://doi.org/10.1103/PhysRevC.109.054610

Nuclide production cross sections are crucial in nuclear research, development, space exploration, and astrophysical investigations. Despite their importance, limited experimental data availability restricts the practicality of phenomenological approaches to comprehensive cross-section estimation. To address this, we propose a Gaussian process-based machine learning (ML) model capable of transferring knowledge from elements with abundant data to those with limited or no experimental data. Our ML model not only enables comprehensive cross-section estimations for various elements but also demonstrates predictive capabilities akin to physics models, even in regions with scarce training data.

Production rates of long-lived radionuclides Be and Al under direct muon-induced spallation in granite quartz and its implications for past high-energy cosmic ray fluxes

Sakurai, Hirohisa*; Kurebayashi, Yutaka*; Suzuki, Soichiro*; Horiuchi, Kazuho*; Takahashi, Yui*; Doshita, Norihiro*; Kikuchi, Satoshi*; Tokanai, Fuyuki*; Iwata, Naoyoshi*; Tajima, Yasushi*; et al.

Physical Review D, 109(10), p.102005_1 - 102005_18, 2024/05

https://doi.org/10.1103/PhysRevD.109.102005

Secular variations of galactic cosmic rays (GCRs) are inseparably associated with the galactic activities and should reflect the environments of the local galactic magnetic field, interstellar clouds, and nearby supernova remnants. The high-energy muons produced in the atmosphere by high-energy GCRs can penetrate deep underground and generate radioisotopes in the rock. As long lived radionuclides such as Be and Al have been accumulating in these rocks, concentrations of Be and Al can be used to estimate the long-term variations in high-energy muon yields, corresponding to those in the high-energy GCRs over a few million years. This study measured the production cross sections for muon induced Be and Al by irradiating positive muons with the momentum of 160 GeV/c on the synthetic silica plates and the granite core at the COMPASS experiment line in CERN SPS. In addition, it the contributions of the direct muon spallation reaction and the nuclear reactions by muon-induced particles on the production of long lived radionuclides in the rocks were clarified.