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Yoon, J.-Y.*; Takeuchi, Yutaro*; Takechi, Ryota*; Han, J.*; Uchiyama, Tomohiro*; Yamane, Yuta*; Kanai, Shun*; Ieda, Junichi; Ohno, Hideo*; Fukami, Shunsuke*
Nature Communications (Internet), 16, p.1171_1 - 1171_8, 2025/02
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)Yamane, Yuta*; Araki, Yasufumi; Fukami, Shunsuke*
Physical Review B, 111(14), p.144412_1 - 144412_9, 2025/00
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Han, J.*; Uchimura, Tomohiro*; Araki, Yasufumi; Yoon, J.-Y.*; Takeuchi, Yutaro*; Yamane, Yuta*; Kanai, Shun*; Ieda, Junichi; Ohno, Hideo*; Fukami, Shunsuke*
Nature Physics, 20(7), p.1110 - 1117, 2024/07
Times Cited Count：19 Percentile：96.80(Physics, Multidisciplinary)Quantum metric and Berry curvature are two fundamental and distinct factors to describe the geometry of quantum eigenstates. While Berry curvature is known for playing crucial roles in several condensed-matter states, quantum metric, which was predicted to induce new classes of topological phenomena, has rarely been touched, particularly in an ambient circumstance. Using a topological chiral antiferromagnet Mn
Sn adjacent to Pt, at room temperature, we successfully manipulate the quantum-metric structure of electronic states through its interplay with the nanoscale spin texture at the MnSn/Pt interface. This is manifested by a time-reversal-odd second-order Hall effect that is robust against extrinsic electron scattering, in contrast to any transport effects from the Berry curvature. We also verify the flexibility of controlling the quantum-metric structure, as the interacting spin texture can be tuned by moderate magnetic fields or by interface engineering via spin-orbit interactions. Our work paves a way for harnessing the quantum-metric structure to unveil emerging topological physics in practical environments and to build applicable nonlinear devices.
Nakata, Koki; Suzuki, Kei
npj Spintronics (Internet), 2, p.11_1 - 11_6, 2024/06
To explore and utilize even dissipation is a crucial issue of spintronics. Here, we shed light on this problem by using a quantum effect, called the magnonic Casimir effect. We show that the dissipation caused by the Gilbert damping decreases the magnon energy gap, and it enhances the magnonic Casimir energy. Then, we find that this magnonic non-Hermitian Casimir effect exhibits an oscillating behavior as a function of the film thickness, and the oscillation is characterized by the exceptional point. Our result suggests that dissipation can serve as a key ingredient of Casimir engineering. Microfabrication technology can control the thickness of thin films and realize the manipulation of the magnonic non-Hermitian Casimir effect. Thus, we pave the way for magnonic Casimir engineering.
Takanashi, Koki
Materia, 62(5), p.301 - 306, 2023/05
no abstracts in English
Lee, S.*; Nakata, Koki; Tchernyshyov, O.*; Kim, S. K.*
Physical Review B, 107(18), p.184432_1 - 184432_12, 2023/05
Times Cited Count：13 Percentile：84.75(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.
Sn nanodotSato, Yuma*; Takeuchi, Yutaro*; Yamane, Yuta*; Yoon, J.-Y.*; Kanai, Shun*; Ieda, Junichi; Ohno, Hideo*; Fukami, Shunsuke*
Applied Physics Letters, 122(12), p.122404_1 - 122404_5, 2023/03
Times Cited Count：5 Percentile：56.18(Physics, Applied)Masuda, Hiroto*; Seki, Takeshi*; Yamane, Yuta*; Modak, R.*; Uchida, Kenichi*; Ieda, Junichi; Lau, Y.-C.*; Fukami, Shunsuke*; Takanashi, Koki
Physical Review Applied (Internet), 17(5), p.054036_1 - 054036_9, 2022/05
Times Cited Count：9 Percentile：62.63(Physics, Applied)The antisymmetric interlayer exchange coupling (AIEC) was recently discovered, playing pivotal roles in magnetization switching of a synthetic antiferromagnet (SAF) through inducing magnetization canting. Large AIEC is reported for perpendicularly magnetized Pt/Co/Ir/Co/Pt with wedge-shaped layers. The effective field of the AIEC is related with symmetric interlayer exchange coupling, providing guides to enhance the AIEC. We develop an extended Stoner-Wohlfarth model for a SAF, revealing key factors in its magnetization switching. Combining the theoretical knowledge and the experimental results, perpendicular magnetization switching is achieved solely by an in-plane magnetic field.
Sn thin films by magneto-optical Kerr effectUchimura, Tomohiro*; Yoon, J.-Y.*; Sato, Yuma*; Takeuchi, Yutaro*; Kanai, Shun*; Takechi, Ryota*; Kishi, Keisuke*; Yamane, Yuta*; DuttaGupta, S.*; Ieda, Junichi; et al.
Applied Physics Letters, 120(17), p.172405_1 - 172405_5, 2022/04
Times Cited Count：24 Percentile：88.33(Physics, Applied)Schreiber, F.*; Meer, H.*; Schmitt, C.*; Ramos, R.*; Saito, Eiji; Baldrati, L.*; Kl
ui, M.*
Physical Review Applied (Internet), 16(6), p.064023_1 - 064023_9, 2021/12
Times Cited Count：4 Percentile：23.69(Physics, Applied)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：136 Percentile：98.80(Chemistry, Physical)
O/YIG structureQi, J.*; Hou, D.*; Chen, Y.*; Saito, Eiji; Jin, X.*
Journal of Magnetism and Magnetic Materials, 534, p.167980_1 - 167980_6, 2021/09
Times Cited Count：3 Percentile：16.18(Materials Science, Multidisciplinary)
Mg
TiOShamoto, Shinichi; Yamauchi, Hiroki; Ikeuchi, Kazuhiko*; Lee, M. K.*; Chang, L.-J.*; Garlea, V. O.*; Hwang, I. Y.*; Lee, K. H.*; Chung, J.-H.*
Journal of the Physical Society of Japan, 90(9), p.093703_1 - 093703_4, 2021/09
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)no abstracts in English
; 
In NQR/NMR and 
Co NMR studySakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Zhu, J.-X.*; Ronning, F.*; Thompson, J. D.*; Ramakrishna, S. K.*; Reyes, A. P.*; Suzuki, Kohei*; Oshima, Yoshiki*; et al.
Physical Review B, 104(8), p.085106_1 - 085106_12, 2021/08
Times Cited Count：5 Percentile：30.04(Materials Science, Multidisciplinary)Antiferromagnetism in a prototypical quantum critical metal CeCoIn is known to be induced by slight substitutions of non-magnetic Zn atoms for In. In nominally 7% Zn substituted CeCoIn, an antiferromagnetic (AFM) state coexists with heavy fermion superconductivity. Heterogeneity of the electronic states is investigated in Zn doped CeCoIn by means of nuclear quadrupole and magnetic resonances (NQR and NMR). Site-dependent NQR relaxation rates 
indicate that the AFM state is locally nucleated around Zn substituents in the matrix of a heavy fermion state, and percolates through the bulk at the AFM transition temperature 
. At lower temperatures, an anisotropic superconducting (SC) gap below the SC transition temperature 
, and the SC state permeates through the AFM regions via a SC proximity effect. Applying an external magnetic field induces a spin-flop transition near 5 T, reducing the volume of the AFM regions. Consequently, a short ranged inhomogeneous AFM state survives and coexists with a paramagnetic Fermi liquid state at high fields.
Sn
thin filmsYoon, J.-Y.*; Takeuchi, Yutaro*; DuttaGupta, S.*; Yamane, Yuta*; Kanai, Shun*; Ieda, Junichi; Ohno, Hideo*; Fukami, Shunsuke*
AIP Advances (Internet), 11(6), p.065318_1 - 065318_6, 2021/06
Times Cited Count：22 Percentile：77.31(Nanoscience & Nanotechnology)Hwang, I. Y.*; Lee, K. H.*; Chung, J.-H.*; Ikeuchi, Kazuhiko*; Garlea, V. O.*; Yamauchi, Hiroki; Akatsu, Mitsuhiro*; Shamoto, Shinichi
Journal of the Physical Society of Japan, 90(6), p.064708_1 - 064708_6, 2021/06
Times Cited Count：5 Percentile：44.31(Physics, Multidisciplinary)no abstracts in English
Si; 
Si NMR studySakai, Hironori; Matsumoto, Yuji*; Haga, Yoshinori; Tokunaga, Yo; Kambe, Shinsaku
Physical Review B, 103(8), p.085114_1 - 085114_8, 2021/02
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)The microscopic origin of a magnetic phase diagram under pressure in a heavy fermion antiferromagnet CeRhSi was investigated using the Si nuclear magnetic resonance (NMR) technique. We investigated the temperature and pressure dependencies of 
-independent local fluctuations caused by the single-site Kondo effect. A universal scaling behavior observed on the energy scale of the local fluctuations in an entire pressure region demonstrates that a characteristic energy scale 
of Kondo interactions monotonically increases by applying pressure without a critical anomaly around the quantum critical pressure 
of antiferromagnetism. Our NMR result agrees with the Doniach picture of the heavy-fermion phase diagram, where the progressive delocalization of the 
-electrons occurs across , accompanied by the development of antiferromagnetic correlations among the -electrons.
symmetry in the tetragonal state of uniaxial strained BaCo
Ni
S
Shamoto, Shinichi; Yamauchi, Hiroki; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Ieda, Junichi
Physical Review Research (Internet), 3(1), p.013169_1 - 013169_9, 2021/02
Meer, H.*; Schreiber, F.*; Schmitt, C.*; Ramos, R.*; Saito, Eiji; Gomonay, O.*; Sinova, J.*; Baldrati, L.*; Klui, M.*
Nano Letters, 21(1), p.114 - 119, 2021/01
Times Cited Count：64 Percentile：95.65(Chemistry, Multidisciplinary)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：29 Percentile：80.61(Physics, Applied)