Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Phys Rev Lett. 2012 Aug 31;109(9):096803. doi: 10.1103/PhysRevLett.109.096803. Epub 2012 Aug 30.
We observe a giant spin-orbit splitting in the bulk and surface states of the noncentrosymmetric semiconductor BiTeI. We show that the Fermi level can be placed in the valence or in the conduction band by controlling the surface termination. In both cases, it intersects spin-polarized bands, in the corresponding surface depletion and accumulation layers. The momentum splitting of these bands is not affected by adsorbate-induced changes in the surface potential. These findings demonstrate that two properties crucial for enabling semiconductor-based spin electronics-a large, robust spin splitting and ambipolar conduction-are present in this material.
我们观察到非中心对称半导体 BiTeI 的体相和表面态中存在巨大的自旋轨道分裂。我们表明，通过控制表面终端，可以将费米能级置于价带或导带中。在这两种情况下，它都与自旋极化带相交，在相应的表面耗尽和积累层中。这些带的动量分裂不受表面势中吸附诱导变化的影响。这些发现表明，这种材料具有实现基于半导体的自旋电子学的两个关键特性 - 大而稳健的自旋分裂和双极性传导。
