Diluted magnetic surface states on semiconductor crystals and its application to spintronics

(1)我们开发了一种超高真空表面磁光克尔效应（UHV-SMOKE）系统来研究表面态的磁性。该方法揭示了钴原子层的磁性敏感地取决于其下面的衬底结构。(2)我们利用自旋分辨光发射光谱和第一性原理计算揭示了非磁性材料铋及其合金（拓扑绝缘体）的表面态是自旋分裂的。(3)利用四尖扫描隧道显微镜（STM）测量表面态输运，在具有较大自旋-轨道相互作用的铋膜表面直接检测到（逆）自旋-霍尔效应。

(1) We have developed an ultra-high-vacuum surface-magneto-optical Kerr effect (UHV-SMOKE) system to investigate magnetic properties of surface states. The method has revealed that the magnetic property of Cobalt atomic layers sensitively depends on the substrate structures beneath them. (2) We have revealed, by using spin-resolved photoemission spectroscopy and the first-principle calculations, that the surface states of non-magnetic materials, Bismuth and its alloys (topological insulators), are spin-split. (3) We have directly detected (inverse) spin-Hall effect on Bismuth film surfaces that have large spin-orbit interaction, by measuring surface-state transport with a four-tip STM (scanning tunneling microscope) apparatus.