arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.01109cond-mat.mes-hallcond-mat.mtrl-sci
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过渡金属二硫属化物/铁磁体双层膜非常规自旋轨道矩的第一性原理计算

Unconventional spin-orbit torque in transition metal dichalcogenide/ferromagnet bilayers from first-principles calculations

Fei Xue, Christoph Rohmann, Junwen Li, Vivek Amin, Paul Haney

摘要:

基于最近在\ch{WTe2} /坡莫合金双层膜系统中观察到的非常规类面外阻尼力矩,我们采用第一性原理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力矩.我们的\ch{WTe2} /Co和\ch{MoTe2} /Co异质结中的自旋轨道转矩的数值计算显示了传统的和新颖的阻尼类torkances(转矩每电场)具有可比的幅度,周围$100~\hbar/2e~(\rm Ω\cdot cm)^{-1}$,电场施加垂直于TMD层的镜面。为了进一步了解阻尼扭矩的来源,我们计算了TMD和Co层之间的自旋电流通量,并发现两个量之间的良好协议。这表明,传统的阻尼类自旋-轨道扭矩的图片,其中扭矩的结果从自旋霍尔效应加上自旋转移扭矩,主要适用于TMD/Co双层系统。

英文摘要:

Motivated by recent observations of unconventional out-of-plane dampinglike torque in \ch{WTe2}/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 \ch{WTe2}/Co and \ch{MoTe2}/Co heterostructures shows both conventional and novel dampinglike torkances (torque per electric field) with comparable magnitude, around $100~\hbar/2e~(\rm Ω\cdot cm)^{-1}$, 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.

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