Giant Rashba splitting originating from the broken symmetry at surfaces

在半导体表面形成的低维纳米结构上，特殊的Rashba效应，如巨大的自旋分裂，已经在实验和理论上进行了研究。我们观察到一些特殊的Rashba效应，比如Rashba自旋100%极化并指向表面法线方向，以及Rashba在没有时间反转对称性的点上分裂，这被认为是产生这种效应的必要条件。这些非凡的效果被认为是由于表面的对称性。我们还证明了Rashba分裂的标志是由原子核附近特殊的电荷不对称决定的。

Peculiar Rashba effects, such as giant spin splitting, on low-dimensional nano-structures, which are formed on semiconductor surfaces, have been investigated both experimentally and theoretically. We observed extraordinary Rashba effects like Rashba spin that is 100 % spin polarized and points along the surface normal direction, and Rashba splitting at a point without time-reversal symmetry, which was believed to be a necessary condition for this effect. These extraordinary effects are concluded to result from the symmetry of the surface. We also showed that the sign of the Rashba splitting is determined by the particular charge asymmetry near the atomic cores.