Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
Department of Physics, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Nano Lett. 2015 Oct 14;15(10):7126-32. doi: 10.1021/acs.nanolett.5b03274. Epub 2015 Oct 1.
Three-dimensional (3D) topological insulators are known for their strong spin-orbit coupling (SOC) and the existence of spin-textured surface states that might be potentially exploited for "topological spintronics." Here, we use spin pumping and the inverse spin Hall effect to demonstrate successful spin injection at room temperature from a metallic ferromagnet (CoFeB) into the prototypical 3D topological insulator Bi2Se3. The spin pumping process, driven by the magnetization dynamics of the metallic ferromagnet, introduces a spin current into the topological insulator layer, resulting in a broadening of the ferromagnetic resonance (FMR) line width. Theoretical modeling of spin pumping through the surface of Bi2Se3, as well as of the measured angular dependence of spin-charge conversion signal, suggests that pumped spin current is first greatly enhanced by the surface SOC and then converted into a dc-voltage signal primarily by the inverse spin Hall effect due to SOC of the bulk of Bi2Se3. We find that the FMR line width broadens significantly (more than a factor of 5) and we deduce a spin Hall angle as large as 0.43 in the Bi2Se3 layer.
三维（3D）拓扑绝缘体以其强大的自旋轨道耦合（SOC）和存在可能被用于“拓扑自旋电子学”的自旋织构表面态而闻名。在这里，我们使用自旋泵浦和反自旋霍尔效应来证明室温下从金属铁磁体（CoFeB）成功地向原型 3D 拓扑绝缘体 Bi2Se3 注入自旋。自旋泵浦过程由金属铁磁体的磁化动力学驱动，将自旋电流引入拓扑绝缘体层，导致铁磁共振（FMR）线宽变宽。通过 Bi2Se3 表面的自旋泵浦的理论建模，以及对测量的自旋-电荷转换信号的角度依赖性的理论建模，表明泵浦的自旋电流首先被表面 SOC 大大增强，然后主要通过 Bi2Se3 体 SOC 的反自旋霍尔效应转换为直流电压信号。我们发现 FMR 线宽显著变宽（超过 5 倍），并且我们推断出 Bi2Se3 层中的自旋霍尔角高达 0.43。
