The ability to engineer new states of matter and control their spintronic properties by electric fields is at the heart of future information technology. Here, we report a gate-tunable spin-galvanic effect in van der Waals heterostructures of graphene with a semimetal of molybdenum ditelluride at room temperature due to an efficient spin-charge conversion process. Measurements in different device geometries with control over the spin orientations exhibit spin-switch and Hanle spin precession behavior, confirming the spin origin of the signal. The control experiments with the pristine graphene channels do not show any such signals. We explain the experimental spin-galvanic signals by theoretical calculations considering the spin-orbit induced spin-splitting in the bands of the graphene in the heterostructure. The calculations also reveal an unusual spin texture in graphene heterostructure with an anisotropic out-of-plane and in-plane spin polarization. These findings open opportunities to utilize graphene-based heterostructures for gate-controlled spintronic devices.

通过电场设计新的物质状态并控制其自旋电子特性的能力是未来信息技术的核心。在这里，我们报告了由于有效的自旋电荷转换过程，在室温下石墨烯与二碲化钼半金属的范德华异质结构中的栅极可调自旋电流效应。在控制自旋方向的不同器件几何结构中的测量显示自旋开关和 Hanle 自旋进动行为，确认信号的自旋起源。原始石墨烯通道的控制实验没有显示任何此类信号。我们通过考虑异质结构中石墨烯带中的自旋轨道诱导的自旋分裂的理论计算来解释实验自旋电流信号。计算还揭示了石墨烯异质结构中不寻常的自旋纹理，具有各向异性的面外和面内自旋极化。这些发现为将基于石墨烯的异质结构用于栅极控制的自旋电子器件提供了机会。