JOPSS - Search Results

Journal Articles

Magnon dynamics in a Skyrmion-textured domain wall of antiferromagnets

Lee, S.*; Nakata, Koki; Tchernyshyov, O.*; Kim, S. K.*

Physical Review B, 107(18), p.184432_1 - 184432_12, 2023/05

https://doi.org/10.1103/PhysRevB.107.184432

Times Cited Count：5 Percentile：87.72(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.

Journal Articles

Intrinsic torques emerging from anomalous velocity in magnetic textures

Araki, Yasufumi; Ieda, Junichi

Physical Review Letters, 127(21), p.277205_1 - 277205_7, 2021/12

https://doi.org/10.1103/PhysRevLett.127.277205

Times Cited Count：5 Percentile：54.81(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 $mathrm{SrRuO_3}$ .

Oral presentation

Laser control of magnonic topological phases in antiferromagnets

Nakata, Koki; Kim, S. K.*; Takayoshi, Shintaro*

no journal, ,

We study the laser control of magnon topological phases induced by the Aharonov-Casher effect in insulating antiferromagnets (AFs). Since the laser electric field can be considered as a time-periodic perturbation, we apply the Floquet theory and perform the inverse frequency expansion by focusing on the high frequency region. Using the obtained effective Floquet Hamiltonian, we study nonequilibrium magnon dynamics away from the adiabatic limit and its effect on topological phenomena. This work enables us to control and design magnonic topological properties away from equilibrium.

Oral presentation