Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.
Nat Mater. 2011 Jun 19;10(7):521-6. doi: 10.1038/nmat3051.
There has been increasing interest in phenomena emerging from relativistic electrons in a solid, which have a potential impact on spintronics and magnetoelectrics. One example is the Rashba effect, which lifts the electron-spin degeneracy as a consequence of spin-orbit interaction under broken inversion symmetry. A high-energy-scale Rashba spin splitting is highly desirable for enhancing the coupling between electron spins and electricity relevant for spintronic functions. Here we describe the finding of a huge spin-orbit interaction effect in a polar semiconductor composed of heavy elements, BiTeI, where the bulk carriers are ruled by large Rashba-like spin splitting. The band splitting and its spin polarization obtained by spin- and angle-resolved photoemission spectroscopy are well in accord with relativistic first-principles calculations, confirming that the spin splitting is indeed derived from bulk atomic configurations. Together with the feasibility of carrier-doping control, the giant-Rashba semiconductor BiTeI possesses excellent potential for application to various spin-dependent electronic functions.
人们对固体中相对论电子产生的现象越来越感兴趣，这些现象有可能对自旋电子学和磁电子学产生影响。其中一个例子是 Rashba 效应，它由于在非中心对称下的自旋轨道相互作用导致电子自旋简并的解除。对于增强与自旋相关的电子和电的耦合，从而实现自旋电子学功能而言，高能量尺度的 Rashba 自旋劈裂是非常理想的。本文报道了在由重元素组成的极性半导体 BiTeI 中发现了巨大的自旋轨道相互作用效应，其中的体载流子受大的 Rashba 型自旋劈裂的控制。通过自旋和角度分辨光发射谱得到的能带劈裂及其自旋极化与相对论第一性原理计算非常吻合，证实了自旋劈裂确实源于体原子构型。加上载流子掺杂控制的可行性，巨型 Rashba 半导体 BiTeI 具有极好的应用潜力，可以应用于各种与自旋相关的电子功能。
