Novakov Steve, Jariwala Bhakti, Vu Nguyen M, Kozhakhmetov Azimkhan, Robinson Joshua A, Heron John T
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States.
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
ACS Appl Mater Interfaces. 2021 Mar 24;13(11):13744-13750. doi: 10.1021/acsami.0c19266. Epub 2021 Mar 11.
Rashba spin current generation emerges in heterostructures of ferromagnets and transition metal dichalcogenides (TMDs) due to an interface polarization and associated inversion symmetry breaking. Recent work exploring the synthesis and transfer of epitaxial films on the top of low layer count 2D materials reveals that atomic potentials from the underlying substrate interface are not completely screened. The extension of this transparency effect to other interfacial phenomena, such as the Rashba effect and associated spin torques, has not yet been demonstrated. Here, we report enhanced spin transfer torques from the Rashba spin current in heterostructures of permalloy (Py) and WSe. We show that insertion of up to two monolayers of WSe enhances the spin transfer torques in a Rashba system by up to 3×, without changing the fieldlike Rashba spin-orbit torque (SOT), a measure of interface polarization. Our results indicate that low layer count TMD films can be used as an interfacial "scattering promoter" in heterostructure interfaces without quenching the original polarization.
由于界面极化和相关的反演对称性破缺，铁磁体与过渡金属二硫属化物（TMDs）的异质结构中会产生 Rashba 自旋电流。最近关于在低层数二维材料顶部外延膜的合成与转移的研究表明，来自底层衬底界面的原子势并未被完全屏蔽。这种透明效应在其他界面现象（如 Rashba 效应和相关的自旋扭矩）中的扩展尚未得到证实。在此，我们报道了在坡莫合金（Py）和 WSe 的异质结构中，来自 Rashba 自旋电流的增强自旋转移扭矩。我们表明，插入多达两个单层的 WSe 可使 Rashba 系统中的自旋转移扭矩增强高达 3 倍，而不会改变类场 Rashba 自旋轨道扭矩（SOT），后者是界面极化的一种度量。我们的结果表明，低层数 TMD 薄膜可在异质结构界面中用作界面“散射促进剂”，而不会消除原始极化。
