Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan.
Phys Rev Lett. 2013 Mar 8;110(10):107204. doi: 10.1103/PhysRevLett.110.107204. Epub 2013 Mar 7.
We investigate the two-dimensional highly spin-polarized electron accumulation layers commonly appearing near the surface of n-type polar semiconductors BiTeX (X=I, Br, and Cl) by angular-resolved photoemission spectroscopy. Because of the polarity and the strong spin-orbit interaction built in the bulk atomic configurations, the quantized conduction-band subbands show giant Rashba-type spin splitting. The characteristic 2D confinement effect is clearly observed also in the valence bands down to the binding energy of 4 eV. The X-dependent Rashba spin-orbit coupling is directly estimated from the observed spin-split subbands, which roughly scales with the inverse of the band-gap size in BiTeX.
我们通过角分辨光发射谱研究了 n 型极性半导体 BiTeX（X=I、Br 和 Cl）表面附近常见的二维高度自旋极化电子积累层。由于极性和体原子结构中的强自旋轨道相互作用，量子化的导带子带表现出巨大的 Rashba 型自旋劈裂。在价带中也可以清楚地观察到特征的 2D 限制效应，直到结合能为 4 eV。从观察到的自旋分裂子带中可以直接估计出 X 依赖的 Rashba 自旋轨道耦合，它大致与 BiTeX 中带隙大小的倒数成正比。
