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Lyons, T. P.*; Puebla, J.*; Yamamoto, Kei; Deacon, R. S.*; Hwang, Y.*; Ishibashi, Koji*; Maekawa, Sadamichi*; Otani, Yoshichika*
Physical Review Letters, 131(19), p.196701_1 - 196701_6, 2023/11
Times Cited Count：0Liao, L.*; Puebla, J.*; Yamamoto, Kei; Kim, J.*; Maekawa, Sadamichi*; Hwang, Y.*; Ba, Y.*; Otani, Yoshichika*
Physical Review Letters, 131(17), p.176701_1 - 176701_6, 2023/10
Times Cited Count：0Yamanoi, Kazuto*; Sakakibara, Yuri*; Fujimoto, Junji*; Matsuo, Mamoru; Nozaki, Yukio*
Applied Physics Express, 16(6), p.063004_1 - 063004_6, 2023/06
Times Cited Count：0 Percentile：0(Physics, Applied)Araki, Yasufumi; Ieda, Junichi
Journal of the Physical Society of Japan, 92(7), p.074705_1 - 074705_9, 2023/06
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)Topological electromagnetism owing to nontrivial momentum-space topology of electrons in insulators gives rise to diverse anomalous magnetoelectric responses. While conventional inductors and capacitors are based on classical electromagnetism described by Maxwell's equations, here we show that topological electromagnetism in combination with spin dynamics in magnets also generates an inductance or a capacitance. We build a generic framework to extract the complex impedance on the basis of topological field theory, and demonstrate the emergence of an inductance or a capacitance in several heterostructure setups. In comparison with the previously-studied emergent inductances in metallic magnets, insulators highly suppress the power loss, because of the absence of Joule heating. We show that the inductance from topological electromagnetism is achieved at low current and high frequency, and is also advantageous in its power efficiency, as characterized by the high quality factor (Q-factor).
Lee, S.*; Nakata, Koki; Tchernyshyov, O.*; Kim, S. K.*
Physical Review B, 107(18), p.184432_1 - 184432_12, 2023/05
Times Cited Count：4 Percentile：90.23(Materials Science, Multidisciplinary)We theoretically investigate the interaction between magnons and a Skyrmion-textured domain wall in a two-dimensional antiferromagnet and elucidate the resultant properties of magnon transport. Using supersymmetric quantum mechanics, we solve the scattering problem of magnons on top of the domain wall and obtain the exact solutions of propagating and bound magnon modes. Then, we find their properties of reflection and refraction in the Skyrmion-textured domain wall, where magnons experience an emergent magnetic field due to its non-trivial spin texture-induced effective gauge field. Finally, we show that the thermal transport decreases as the domain wall's chirality increases. Our results suggest that the thermal transport of an antiferromagnet is tunable by modulating the Skyrmion charge density of the domain wall.
Yama, Masaki*; Matsuo, Mamoru; Kato, Takeo*
Physical Review B, 107(17), p.174414_1 - 174414_15, 2023/05
Times Cited Count：1 Percentile：0(Materials Science, Multidisciplinary)Nakata, Koki; Suzuki, Kei
Physical Review Letters, 130(9), p.096702_1 - 096702_6, 2023/03
Times Cited Count：2 Percentile：61.99(Physics, Multidisciplinary)Quantum fluctuations of quantum fields induce a zero-point energy shift under spatial boundary conditions. This quantum phenomenon, called the Casimir effect, has been attracting much attention beyond the hierarchy of energy scales, whereas its application to spintronics has not yet been investigated enough, particularly to ferrimagnetic thin films. Here we fill this gap. Using the lattice field theory, we investigate the Casimir effect induced by quantum fields for magnons and find that the magnonic Casimir effect can arise not only in antiferromagnets but also in ferrimagnets (e.g., YIG). Thus, we pave the way for magnonic Casimir engineering.
Ishikawa, Takuto*; Matsuo, Mamoru; Kato, Takeo*
Physical Review B, 107(5), p.054426_1 - 054426_9, 2023/02
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)Lee, O.*; Yamamoto, Kei; Umeda, Maki; Zollitsch, C. W.*; Elyasi, M.*; Kikkawa, Takashi*; Saito, Eiji; Bauer, G. E. W.*; Kurebayashi, Hidekazu*
Physical Review Letters, 130(4), p.046703_1 - 046703_6, 2023/01
Times Cited Count：5 Percentile：80.44(Physics, Multidisciplinary)Yamamoto, Kei; Maekawa, Sadamichi*
Annalen der Physik, 11 Pages, 2023/00
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)Ominato, Yuya*; Yamakage, Ai*; Matsuo, Mamoru
Physical Review B, 106(16), p.L161406_1 - L161406_6, 2022/10
Times Cited Count：7 Percentile：73.14(Materials Science, Multidisciplinary)Fujimoto, Junji*; Funaki, Hiroshi*; Koshibae, Wataru*; Matsuo, Mamoru; Maekawa, Sadamichi*
IEEE Transactions on Magnetics, 58(8), p.1500407_1 - 1500407_7, 2022/08
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)Puebla, J.*; Hwang, Y.*; Maekawa, Sadamichi*; Otani, Yoshichika*
Applied Physics Letters, 120(22), p.220502_1 - 220502_9, 2022/05
Times Cited Count：18 Percentile：92.05(Physics, Applied)Nakata, Koki; Onuma, Yuichi*; Kim, S. K.*
Physical Review B, 105(18), p.184409_1 - 184409_7, 2022/05
Times Cited Count：2 Percentile：34.67(Materials Science, Multidisciplinary)We show that the ratio of the thermal to spin transport coefficient of magnons in insulating magnets exhibits a different behavior from the linear response and the universal law breaks down in the strong nonlinear regime.
Nakata, Koki; Onuma, Yuichi*
Physical Review B, 105(14), p.144436_1 - 144436_7, 2022/04
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)Using a junction of the ferromagnetic insulators irradiated by linearly polarized laser, we propose a method for the generation of dc and ac spin currents of magnons across the junction interface, and provide an analytical formula for magnon transport induced by the inversion symmetry breaking.
Elyasi, M.*; Saito, Eiji; Bauer, G. E. W.*
Physical Review B, 105(5), p.054403_1 - 054403_12, 2022/02
Times Cited Count：7 Percentile：77.62(Materials Science, Multidisciplinary)Funato, Takumi*; Matsuo, Mamoru
Journal of Magnetism and Magnetic Materials, 540, p.168436_1 - 168436_7, 2021/12
Times Cited Count：3 Percentile：25.69(Materials Science, Multidisciplinary)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 
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Shamoto, Shinichi; Ieda, Junichi
CROSS T&T, (69), p.35 - 39, 2021/10
no abstracts in English
Nakata, Koki
Physical Review B, 104(10), p.104402_1 - 104402_12, 2021/09
Times Cited Count：1 Percentile：7.92(Materials Science, Multidisciplinary)Combining advanced technologies of optics and antiferromagnetic spintronics, we present a method to realize ultrafast Josephson spin currents through the optomagnonic Barnett effect by using macroscopic coherence of magnon condensates.
