Xue Fei, Rohmann Christoph, Li Junwen, Amin Vivek, Haney Paul
Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Institute for Research in Electronics and Applied Physics & Maryland Nanocenter, University of Maryland, College Park, MD 20742.
Phys Rev B. 2020;102(1). doi: 10.1103/physrevb.102.014401.
Motivated by recent observations of unconventional out-of-plane dampinglike torque in WTe/Permalloy bilayer systems, we calculate the spin-orbit torque generated in two-dimensional transition metal dichalcogenide (TMD)/ferromagnet heterostructures using first-principles methods and linear response theory. Our numerical calculation of spin-orbit torques in WTe/Co and MoTe/Co heterostructures shows both conventional and novel dampinglike torkances (torque per electric field) with comparable magnitude, around one hundred /2 (Ω · cm), for an electric-field applied perpendicular to the mirror plane of the TMD layer. To gain further insight into the source of dampinglike torque, we compute the spin current flux between the TMD and Co layers and find good agreement between the two quantities. This indicates that the conventional picture of dampinglike spin-orbit torque, whereby the torque results from the spin Hall effect plus spin transfer torque, largely applies to TMD/Co bilayer systems.
受近期在WTe/坡莫合金双层系统中观察到的非常规面外类阻尼转矩的启发，我们使用第一性原理方法和线性响应理论，计算了二维过渡金属二硫属化物（TMD）/铁磁体异质结构中产生的自旋轨道转矩。我们对WTe/Co和MoTe/Co异质结构中自旋轨道转矩的数值计算表明，对于垂直于TMD层镜平面施加的电场，传统的和新型的类阻尼转矩（每电场的转矩）大小相当，约为100 /2（Ω·cm）。为了进一步深入了解类阻尼转矩的来源，我们计算了TMD层和Co层之间的自旋电流通量，并发现这两个量之间有很好的一致性。这表明，类阻尼自旋轨道转矩的传统图景，即转矩由自旋霍尔效应加自旋转移转矩产生，在很大程度上适用于TMD/Co双层系统。
