Ghiasi Talieh S, Kaverzin Alexey A, Blah Patrick J, van Wees Bart J
Zernike Institute for Advanced Materials , University of Groningen , Groningen , 9747 AG , The Netherlands.
Nano Lett. 2019 Sep 11;19(9):5959-5966. doi: 10.1021/acs.nanolett.9b01611. Epub 2019 Aug 27.
The proximity of a transition-metal dichalcogenide (TMD) to graphene imprints a rich spin texture in graphene and complements its high-quality charge/spin transport by inducing spin-orbit coupling (SOC). Rashba and valley-Zeeman SOCs are the origin of charge-to-spin conversion mechanisms such as the Rashba-Edelstein effect (REE) and spin Hall effect (SHE). In this work, we experimentally demonstrate for the first time charge-to-spin conversion due to the REE in a monolayer WS-graphene van der Waals heterostructure. We measure the current-induced spin polarization up to room temperature and control it by a gate electric field. Our observation of the REE and the inverse of the effect (IREE) is accompanied by the SHE, which we discriminate by symmetry-resolved spin precession under oblique magnetic fields. These measurements also allow for the quantification of the efficiencies of charge-to-spin conversion by each of the two effects. These findings are a clear indication of induced Rashba and valley-Zeeman SOC in graphene that lead to the generation of spin accumulation and spin current without using ferromagnetic electrodes. These realizations have considerable significance for spintronic applications, providing accessible routes toward all-electrical spin generation and manipulation in two-dimensional materials.
过渡金属二硫属化物（TMD）与石墨烯的接近在石墨烯中赋予了丰富的自旋纹理，并通过诱导自旋轨道耦合（SOC）来补充其高质量的电荷/自旋输运。Rashba和谷塞曼SOC是诸如Rashba-Edelstein效应（REE）和自旋霍尔效应（SHE）等电荷到自旋转换机制的起源。在这项工作中，我们首次通过实验证明了在单层WS-石墨烯范德华异质结构中由于REE导致的电荷到自旋的转换。我们测量了高达室温的电流诱导自旋极化，并通过栅极电场对其进行控制。我们对REE及其逆效应（IREE）的观察伴随着SHE，我们通过在倾斜磁场下的对称分辨自旋进动来区分它们。这些测量还允许对两种效应各自的电荷到自旋转换效率进行量化。这些发现清楚地表明石墨烯中诱导的Rashba和谷塞曼SOC导致了自旋积累和自旋电流的产生，而无需使用铁磁电极。这些成果对于自旋电子学应用具有相当重要的意义，为二维材料中的全电自旋产生和操控提供了可行的途径。
