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Kitazawa, Takafumi; Ikeda, Yoichi*; Sakakibara, Toshiro*; Matsuo, Akira*; Shimizu, Yusei*; Tokunaga, Yo; Haga, Yoshinori; Kindo, Koichi*; Nambu, Yusuke*; Ikeuchi, Kazuhiko*; et al.
Physical Review B, 108(8), p.085105_1 - 085105_7, 2023/08
Masuda, Hiroto*; Yamane, Yuta*; Seki, Takeshi*; Raab, K.*; Dohi, Takaaki*; Modak, R.*; Uchida, Kenichi*; Ieda, Junichi; Klui, M.*; Takanashi, Koki
Applied Physics Letters, 122(16), p.162402_1 - 162402_7, 2023/04
Times Cited Count:1 Percentile:54.89(Physics, Applied)Watanabe, Jin*; Araki, Yasufumi; Kobayashi, Koji*; Ozawa, Akihiro*; Nomura, Kentaro*
Journal of the Physical Society of Japan, 91(8), p.083702_1 - 083702_5, 2022/08
Times Cited Count:3 Percentile:58.88(Physics, Multidisciplinary)We investigate magnetic orderings on kagome lattice numerically from the tight-binding Hamiltonian of electrons, governed by the filling factor and spin-orbit coupling (SOC) of electrons. We find that even a simple kagome lattice model can host both ferromagnetic and noncollinear antiferromagnetic orderings depending on the electron filling, reflecting gap structures in the Dirac and flat bands characteristic to the kagome lattice. Kane-Mele- or Rashba-type SOC tends to stabilize noncollinear orderings, such a magnetic spirals and 120-degree antiferromagnetic orderings, due to the effective Dzyaloshinskii-Moriya interaction from SOC. The obtained phase structure helps qualitative understanding of magnetic orderings in various kagome-layered materials with Weyl or Dirac electrons.
Yamane, Yuta*; Fukami, Shunsuke*; Ieda, Junichi
Physical Review Letters, 128(14), p.147201_1 - 147201_6, 2022/04
Times Cited Count:3 Percentile:58.88(Physics, Multidisciplinary)We extend the theory of emergent inductance, which has recently been discovered in spiral magnets, to arbitrary magnetic textures by taking into account spin-orbit couplings arising in the absence of spatial inversion symmetry. We propose a new concept of spin-orbit emergent inductance, which can be formulated as originating from a dynamical Aharonov-Casher phase of an electron in ferromagnets. The spin-orbit emergent inductance universally arises in the coexistence of magnetism and the spin-orbit couplings, even with spatially uniform magnetization, allowing its stable operation in wide ranges of temperature and frequency. Revisiting the widely studied systems involving ferromagnets with spatial inversion asymmetry, with the new perspective offered by our work, will lead to opening a new paradigm in the study of spin-orbit physics and the spintronics-based power management in ultrawideband frequency range.
Yamanouchi, Michihiko*; Araki, Yasufumi; Sakai, Takaki*; Uemura, Tetsuya*; Ota, Hiromichi*; Ieda, Junichi
Science Advances (Internet), 8(15), p.eabl6192_1 - eabl6192_6, 2022/04
Times Cited Count:7 Percentile:73.76(Multidisciplinary Sciences)In a ferromagnetic Weyl metal SrRuO, a large effective magnetic field exerted on a magnetic domain wall (DW) by current has been reported. We show that the ratio of to current density exhibits nonmonotonic temperature dependence and surpasses those of conventional spin-transfer torques and spin-orbit torques. This enhancement is described well by topological Hall torque (THT), which is exerted on a DW by Weyl electrons emerging around Weyl points when an electric field is applied across the DW. The ratio of the arising from the THT to current density is over one order of magnitude higher than that originating from spin-transfer torques and spin-orbit torques reported in metallic systems, showing that the THT may provide a better way for energy-efficient manipulation of magnetization in spintronics devices.
Araki, Yasufumi; Ieda, Junichi
Physical Review Letters, 127(21), p.277205_1 - 277205_7, 2021/12
Times Cited Count:5 Percentile:41.09(Physics, Multidisciplinary)Momentum-space topology of electrons under strong spin-orbit coupling contributes to the electrically induced torques exerting on magnetic textures insensitively to disorder or thermal fluctuation. We present a direct connection between band topology and the torques by classifying the whole torques phenomenologically. As well as the intrinsic anomalous Hall effect, the torques also emerge intrinsically from the anomalous velocity of electrons regardless of a nonequilibrium transport current. We especially point out the intrinsic contribution arising exclusively in magnetic textures, which we call the "topological Hall torque (THT)". The THT emerges in bulk crystals without any interface or surface structures. We numerically demonstrate the enhancement of the THT in comparison with the conventional spin-transfer torque in the bulk metallic ferromagnet, which accounts for the giant current-induced torque measured in ferromagnetic .
Saito, Junichi; Kobayashi, Yohei*; Shibutani, Hideo*
Materials Transactions, 62(10), p.1524 - 1532, 2021/10
Times Cited Count:5 Percentile:41.35(Materials Science, Multidisciplinary)no abstracts in English
Takeuchi, Yutaro*; Yamane, Yuta*; Yoon, J.-Y.*; Ito, Ryuichi*; Jinnai, Butsurin*; Kanai, Shun*; Ieda, Junichi; Fukami, Shunsuke*; Ohno, Hideo*
Nature Materials, 20(10), p.1364 - 1370, 2021/10
Times Cited Count:81 Percentile:98.79(Chemistry, Physical)Kurebayashi, Daichi*; Araki, Yasufumi; Nomura, Kentaro*
Journal of the Physical Society of Japan, 90(8), p.084702_1 - 084702_9, 2021/08
Times Cited Count:8 Percentile:61.42(Physics, Multidisciplinary)We theoretically study current- and charge-induced spin torque in magnetic Weyl semimetals. In magnetic Weyl semimetals (WSM), topologically nontrivial band structure mediates anomalous coupling between magnetization and transport, making WSMs preferable for spintronics systems. In this paper, we determine all current-induced spin torques including spin-orbit torque and spin-transfer torque, up to first order with respect to spatial and temporal derivatives and electrical currents. We also calculate the charge-induced spin torque microscopically. We find the charge-induced spin torque originates from the chiral anomaly due to the correspondence between spin operators and axial current operators in our model.
Yama, Masaki*; Tatsuno, Masahiro*; Kato, Takeo*; Matsuo, Mamoru
Physical Review B, 104(5), p.054410_1 - 054410_9, 2021/08
Times Cited Count:7 Percentile:51.66(Materials Science, Multidisciplinary)Araki, Yasufumi; Misawa, Takahiro*; Nomura, Kentaro*
Physical Review Research (Internet), 3(2), p.023219_1 - 023219_15, 2021/06
We theoretically propose the long-range spin transport mediated by the gapless surface states of topological Dirac semimetal (TDSM). Low-dissipation spin current is a building block of next-generation spintronics devices. While conduction electrons in metals and spin waves in ferromagnetic insulators (FMIs) are the major carriers of spin current, their propagation length is inevitably limited due to the Joule heating or the Gilbert damping. In order to suppress dissipation and realize long-range spin transport, we here make use of the spin-helical surface states of TDSMs, such as CdAs and NaBi, which are robust against disorder. Based on a junction of two FMIs connected by a TDSM, we demonstrate that the magnetization dynamics in one FMI induces a spin current on the TDSM surface flowing to the other FMI. By both the analytical transport theory on the surface and the numerical simulation of real-time evolution in the bulk, we find that the induced spin current takes a universal semi-quantized value that is insensitive to the microscopic coupling structure between the FMI and the TDSM. We show that this surface spin current is robust against disorder over a long range, which indicates that the TDSM surface serves as a promising system for realizing spintronics devices.
Araki, Yasufumi; Suenaga, Daiki*; Suzuki, Kei; Yasui, Shigehiro*
Physical Review Research (Internet), 3(2), p.023098_1 - 023098_17, 2021/05
Spins of relativistic fermions are related to their orbital degrees of freedom. In order to quantify the effect of hybridization between relativistic and nonrelativistic degrees of freedom on spin-orbit coupling, we focus on the spin-orbital (SO) crossed susceptibility arising from spin-orbit coupling. The SO crossed susceptibility is defined as the response function of their spin polarization to the "orbital" magnetic field, namely the effect of magnetic field on the orbital motion of particles as the vector potential. Once relativistic and nonrelativistic fermions are hybridized, their SO crossed susceptibility gets modified at the Fermi energy around the band hybridization point, leading to spin polarization of nonrelativistic fermions as well. These effects are enhanced under a dynamical magnetic field that violates thermal equilibrium, arising from the interband process permitted by the band hybridization. Its experimental realization is discussed for Dirac electrons in solids with slight breaking of crystalline symmetry or doping, and also for quark matter including dilute heavy quarks strongly hybridized with light quarks, arising in a relativistic heavy-ion collision process.
Saito, Junichi; Kobayashi, Yohei*; Shibutani, Hideo*
Nihon Kinzoku Gakkai-Shi, 85(3), p.110 - 119, 2021/03
Times Cited Count:1 Percentile:8.06(Metallurgy & Metallurgical Engineering)Ramos, R.*; Makiuchi, Takahiko*; Kikkawa, Takashi*; Daimon, Shunsuke*; Oyanagi, Koichi*; Saito, Eiji
Applied Physics Letters, 117(24), p.242402_1 - 242402_5, 2020/12
Times Cited Count:1 Percentile:5.55(Physics, Applied)Schreiber, F.*; Baldrati, L.*; Schmitt, C.*; Ramos, R.*; Saito, Eiji; Lebrun, R.*; Klui, M.*
Applied Physics Letters, 117(8), p.082401_1 - 082401_5, 2020/08
Times Cited Count:25 Percentile:84.2(Physics, Applied)Baldrati, L.*; Schmitt, C.*; Gomonay, O.*; Lebrun, R.*; Ramos, R.*; Saito, Eiji; Sinova, J.*; Klui, M.*
Physical Review Letters, 125(7), p.077201_1 - 077201_6, 2020/08
Times Cited Count:36 Percentile:91.79(Physics, Multidisciplinary)Baldrati, L.*; Gomonay, O.*; Ross, A.*; Filianina, M.*; Lebrun, R.*; Ramos, R.*; Leveille, C.*; Fuhrmann, F.*; Forrest, T. R.*; Maccherozzi, F.*; et al.
Physical Review Letters, 123(17), p.177201_1 - 177201_6, 2019/10
Times Cited Count:118 Percentile:98.44(Physics, Multidisciplinary)Konki, J.*; Khuyagbaatar, J.*; Uusitalo, J.*; Greenlees, P. T.*; Auranen, K.*; Badran, H.*; Block, M.*; Briselet, R.*; Cox, D. M.*; Dasgupta, M.*; et al.
Physics Letters B, 764, p.265 - 270, 2017/01
Times Cited Count:17 Percentile:79.42(Astronomy & Astrophysics)Kawasuso, Atsuo
Hoshasen To Sangyo, (139), p.18 - 22, 2015/12
no abstracts in English
Kido, Kentaro; Kasahara, Kento*; Yokogawa, Daisuke*; Sato, Hirofumi*
Journal of Chemical Physics, 143(1), p.014103_1 - 014103_9, 2015/07
Times Cited Count:5 Percentile:14.86(Chemistry, Physical)