Weißenhofer Markus, Nowak Ulrich
Department of Physics, University of Konstanz, 78457, Konstanz, Germany.
Sci Rep. 2022 Apr 26;12(1):6801. doi: 10.1038/s41598-022-10550-z.
We explore the dynamics of skyrmions with various topological charges induced by a temperature gradient in an ultra-thin insulating magnetic film. Combining atomistic spin simulations and analytical calculations we find a topology-dependent skyrmion Seebeck effect: while skyrmions and antiskyrmions move to the hot regime, a topologically trivial localized spin structure moves to the cold regime. We further reveal the emergence of a skyrmion Nernst effect, i.e. finite, topology-dependent velocities transverse to the direction of the temperature gradient. These findings are in agreement with accompanying simulations of skyrmionic motion induced by monochromatic magnon currents, allowing us to demonstrate that the magnonic spin Seebeck effect is responsible for both, skyrmion Seebeck and Nernst effect. Furthermore we employ scattering theory together with Thiele's equation to identify linear momentum transfer from the magnons to the skyrmion as the dominant contribution and to demonstrate that the direction of motion depends on the topological magnon Hall effect and the topological charge of the skyrmion.
我们研究了超薄绝缘磁性薄膜中由温度梯度诱导的具有各种拓扑电荷的斯格明子的动力学。结合原子自旋模拟和解析计算，我们发现了一种依赖于拓扑结构的斯格明子塞贝克效应：当斯格明子和反斯格明子向高温区域移动时，一种拓扑平凡的局域自旋结构向低温区域移动。我们进一步揭示了斯格明子能斯特效应的出现，即垂直于温度梯度方向的有限的、依赖于拓扑结构的速度。这些发现与由单色磁振子电流诱导的斯格明子运动的伴随模拟结果一致，这使我们能够证明磁振子自旋塞贝克效应是斯格明子塞贝克效应和能斯特效应的共同原因。此外，我们利用散射理论和蒂勒方程来确定从磁振子到斯格明子的线性动量转移是主要贡献，并证明运动方向取决于拓扑磁振子霍尔效应和斯格明子的拓扑电荷。
