基于外尔半金属的全二维异质结自旋轨道转矩

垂直磁各向异性层的翻转是实现高密度自旋轨道转矩磁性随机存储的关键。近年来，拓扑保护的外尔半金属逐渐成为凝聚态物理的热点。实验表明，当电场沿着拓扑半金属WTe2的费米弧方向，WTe2的表面存在来源于自旋动量锁定的自旋积累。但是到目前为止，并无实验研究拓扑保护的半金属直接电流驱动具有垂直磁各向异性的磁矩翻转的研究。近年发现的二维伊辛铁磁体金属Fe3GeTe2具有优良的垂直磁各向异性。因此本课题拟采用全二维范德瓦尔斯异质结，WTe2/Fe3GeTe2作为自旋轨道转矩的研究对象。拟采用二倍频霍尔效应提取外尔半金属WTe2对Fe3GeTe2各向异性的自旋轨道力矩。采用电场(费米面高度)、温度(拓扑相变)、晶向(各向异性费米弧自旋积累)等因素，调控电流驱动Fe3GeTe2垂直磁矩的翻转，解析外尔半金属费米弧的自旋积累对自旋轨道转矩的物理机制。本课题的研究结果将为拓扑半金属在自旋电子学的应用提供指导。

As the most important strategy in Spintronics, switching of magnets with perpendicular magnetic anisotropy is the central part of the high-density magnetic recording of spin-orbit-torque magnetic random access memory (SOT-MRAM). Recently, topological Weyl semimetals become popular in condensed matters. The experiments show that there are spin accumulations on the surface of topological Weyl semimetal WTe2 due to the spin momentum locking when the electric field is along the direction of Fermi arc. However, so far no experiment on topological Weyl semimetal has been performed to study the current induced switching of magnetization with perpendicular magnetic anisotropy. It is discovered that the 2D Ising ferromagnet Fe3GeTe2 shows superior perpendicular magnetic anisotropy. In this proposal, we plan to investigate the spin-orbit torques in fully two dimensional van de Wals heterostructures WTe2/Fe3GeTe2. We plan to use the second harmonic Hall voltage in heterostructure to extract the anisotropy of spin-orbit-torque. And electric field (location of Fermi surface), temperature (topological phase transition), in-plane current direction (anisotropic spin accumulation of Fermi arc) are used to modulate the current induced switching of the moments of Fe3GeTe2, to understand the physical mechanism of spin accumulation in Fermi arc of Weyl semimetal on spin-orbit-torque. This proposal will provide useful information for the potential application of topological Weyl semimetals in spintronics.