arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.13266cond-mat.mtrl-scicond-mat.mes-hallphysics.comp-ph
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从理论计算得到的拓扑不同的磁性Skyrmionic织构的高分辨率隧穿自旋输运特性

High-resolution tunneling spin transport characteristics of topologically distinct magnetic skyrmionic textures from theoretical calculations

Krisztián Palotás, Levente Rózsa, Eszter Simon, László Szunyogh

摘要:

在自旋极化扫描隧道显微镜(SP-STM)的框架下,采用3D-WKB标量电荷和矢量自旋输运理论,研究了拓扑结构不同的实空间磁性Skyrmionic织构的高分辨率隧穿电子自旋输运性质(纵向自旋流(LSC)和自旋转移矩(STT)图).在我们的理论研究中,我们考虑了(Pt $_{0.95}$ Ir $_{0.05}$)/Fe/Pd(111)双磁性薄膜中具有不同拓扑电荷($Q=-3,-2,-1,0,1,2$)的亚稳Skyrmionic自旋结构.使用面外磁化SP-STM尖端,发现作用于磁纹理自旋的LSC矢量和所有STT矢量分量的映射表现出与skyrmionic对象相同的拓扑结构。相比之下,平面内磁化尖端通常不会导致自旋输运矢量图,其在拓扑上等同于底层自旋结构,除了在样品和尖端的自旋极化之间的特定关系处作用于skyrmionic纹理的自旋的LSC矢量。自旋输运矢量的大小表现出密切的关系,无论skyrmionic拓扑结构的电荷电流SP-STM图像。此外,我们发现,STT的效率(扭矩/电流比)作用于自旋的skyrmions可以达到大的值高达$\sim$ 25 meV/ $μ$ A($\sim$ 0.97 $h/e$)以上的边缘的磁性物体,但它显着变化之间的大和小的值取决于SP-STM尖端以上的拓扑自旋纹理的横向位置。一个简单的表达式的STT效率的介绍,以解释其变化。我们计算的自旋输运矢量可用于研究自旋极化隧道电流诱导的自旋动力学的拓扑不同的表面磁性skyrmionic纹理。

英文摘要:

High-resolution tunneling electron spin transport properties (longitudinal spin current (LSC) and spin transfer torque (STT) maps) of topologically distinct real-space magnetic skyrmionic textures are reported by employing a 3D-WKB combined scalar charge and vector spin transport theory in the framework of spin-polarized scanning tunneling microscopy (SP-STM). For our theoretical investigation metastable skyrmionic spin structures with various topological charges ($Q=-3,-2,-1,0,1,2$) in the (Pt$_{0.95}$Ir$_{0.05}$)/Fe/Pd(111) ultrathin magnetic film are considered. Using an out-of-plane magnetized SP-STM tip it is found that the maps of the LSC vectors acting on the spins of the magnetic textures and all STT vector components exhibit the same topology as the skyrmionic objects. In contrast, an in-plane magnetized tip generally does not result in spin transport vector maps that are topologically equivalent to the underlying spin structure, except for the LSC vectors acting on the spins of the skyrmionic textures at a specific relation between the spin polarizations of the sample and the tip. The magnitudes of the spin transport vector quantities exhibit close relations to charge current SP-STM images irrespectively of the skyrmionic topologies. Moreover, we find that the STT efficiency (torque/current ratio) acting on the spins of the skyrmions can reach large values up to $\sim$25 meV/$μ$A ($\sim$0.97 $h/e$) above the rim of the magnetic objects, but it considerably varies between large and small values depending on the lateral position of the SP-STM tip above the topological spin textures. A simple expression for the STT efficiency is introduced to explain its variation. Our calculated spin transport vectors can be used for the investigation of spin-polarized tunneling-current-induced spin dynamics of topologically distinct surface magnetic skyrmionic textures.

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