| 研究実績の概要 |
We formulated a general microscopic approach to spin-orbit torques in ferromagnet/heavy-metal bilayers in linear response to electric current or electric field [Physical Review B 95, 094401 (2017)]. The torques are directly related to a local spin polarization of conduction electrons, which is computed from generalized Kubo-Streda formulas.
We have developed a multiscale magnetization dynamics simulation approach that can be applied to large systems with spin spiral structures that vary locally on small length scales [Physical Review B 94, 184415 (2016)]. We have shown that in a system with a Dzyaloshinskii-Moriya interaction leading to spin spirals, the simulated multiscale result is in good agreement with the analytical calculation.
We developed a theory of Skyrmion Hall effect, which has been successfully observed by time-resolved x-ray microscopy [Nature Physics, 13, 170 (2017)]. We find that skyrmions move at a well-defined Skyrmion Hall angle, but in contrast to conventional theoretical expectations, it increases linearly with velocity. We explained our observation based on internal mode excitations in combination with a field-like spin-orbit torque, showing that one must go beyond the usual rigid skyrmion description to understand the dynamics.
|
