Li Yan, Li Yang, Li Peng, Fang Bin, Yang Xu, Wen Yan, Zheng Dong-Xing, Zhang Chen-Hui, He Xin, Manchon Aurélien, Cheng Zhao-Hua, Zhang Xi-Xiang
Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Nat Commun. 2021 Jan 22;12(1):540. doi: 10.1038/s41467-020-20840-7.
Nonmagnetic Rashba systems with broken inversion symmetry are expected to exhibit nonreciprocal charge transport, a new paradigm of unidirectional magnetoresistance in the absence of ferromagnetic layer. So far, most work on nonreciprocal transport has been solely limited to cryogenic temperatures, which is a major obstacle for exploiting the room-temperature two-terminal devices based on such a nonreciprocal response. Here, we report a nonreciprocal charge transport behavior up to room temperature in semiconductor α-GeTe with coexisting the surface and bulk Rashba states. The combination of the band structure measurements and theoretical calculations strongly suggest that the nonreciprocal response is ascribed to the giant bulk Rashba spin splitting rather than the surface Rashba states. Remarkably, we find that the magnitude of the nonreciprocal response shows an unexpected non-monotonical dependence on temperature. The extended theoretical model based on the second-order spin-orbit coupled magnetotransport enables us to establish the correlation between the nonlinear magnetoresistance and the spin textures in the Rashba system. Our findings offer significant fundamental insight into the physics underlying the nonreciprocity and may pave a route for future rectification devices.
具有反演对称性破缺的非磁性 Rashba 系统有望展现出非互易电荷输运，这是一种在没有铁磁层情况下的单向磁电阻新范式。到目前为止，大多数关于非互易输运的研究仅局限于低温，这是基于这种非互易响应开发室温两端器件的主要障碍。在此，我们报道了在同时存在表面和体 Rashba 态的半导体α-GeTe 中，高达室温的非互易电荷输运行为。能带结构测量和理论计算的结合有力地表明，非互易响应归因于巨大的体 Rashba 自旋分裂而非表面 Rashba 态。值得注意的是，我们发现非互易响应的幅度对温度呈现出意想不到的非单调依赖性。基于二阶自旋轨道耦合磁输运的扩展理论模型使我们能够建立 Rashba 系统中非线性磁电阻与自旋纹理之间的关联。我们的发现为非互易性背后的物理提供了重要的基本见解，并可能为未来的整流器件开辟一条道路。
