论文标题
3D，5D和4F金属异质结构中的巨型轨道厅效应以及轨道转换
Giant orbital Hall effect and orbital-to-spin conversion in 3d, 5d, and 4f metallic heterostructures
论文作者
论文摘要
轨道大厅的效应为自旋大厅效应提供了一种替代手段，以将电荷电流转换为角动量流动。最近，在3D过渡金属中已经确定了轨道大厅效应的引人注目的特征。在这里，我们报告了一项系统的研究，该研究对包括3D，5D金属的异质结构的轨道电流的产生，传播和转化。我们表明，CR的轨道大厅的电导率达到了5*10^5 ohm^{ - 1} M^{ - 1}的巨大值，并且PT除了旋转厅效应外，还具有强轨道霍尔效应。进行的测量是非磁性CR，MN和PT层厚度的函数，而铁磁CO和Ni层则揭示了轨道和自旋电流如何竞争或相互协助，以确定作用在磁层上的自旋轨道扭矩。我们进一步展示了如何通过在非磁性层和磁层之间引入4 F垫片来大大调制这种相互作用。 GD和TB充当非常有效的轨道到旋转电流转换器，将CR产生的自旋轨道扭矩增加了4倍，并逆转了PT产生的扭矩的符号。为了解释我们的结果，我们提出了一个广义的漂移扩散模型，该模型包括自旋和轨道大厅效应，并描述了它们由自旋轨道耦合介导的互转换。
The orbital Hall effect provides an alternative means to the spin Hall effect to convert a charge current into a flow of angular momentum. Recently, compelling signatures of orbital Hall effects have been identified in 3d transition metals. Here, we report a systematic study of the generation, transmission, and conversion of orbital currents in heterostructures comprising 3d, 5d, and 4f metals. We show that the orbital Hall conductivity of Cr reaches giant values of the order of 5*10^5 Ohm^{-1} m^{-1} and that Pt presents a strong orbital Hall effect in addition to the spin Hall effect. Measurements performed as a function of thickness of nonmagnetic Cr, Mn, and Pt layers and ferromagnetic Co and Ni layers reveal how the orbital and spin currents compete or assist each other in determining the spin-orbit torques acting on the magnetic layer. We further show how this interplay can be drastically modulated by introducing 4 f spacers between the nonmagnetic and magnetic layers. Gd and Tb act as very efficient orbital-to-spin current converters, boosting the spin-orbit torques generated by Cr by a factor of 4 and reversing the sign of the torques generated by Pt. To interpret our results, we present a generalized drift-diffusion model that includes both spin and orbital Hall effects and describes their interconversion mediated by spin-orbit coupling.
