Institute of Strength Physics and Materials Science, 634021, Tomsk, Russia.
Phys Rev Lett. 2012 Jun 15;108(24):246802. doi: 10.1103/PhysRevLett.108.246802. Epub 2012 Jun 13.
Spintronics is aimed at actively controlling and manipulating the spin degrees of freedom in semiconductor devices. A promising way to achieve this goal is to make use of the tunable Rashba effect that relies on the spin-orbit interaction in a two-dimensional electron system immersed in an inversion-asymmetric environment. The spin-orbit-induced spin splitting of the two-dimensional electron state provides a basis for many theoretically proposed spintronic devices. However, the lack of semiconductors with large Rashba effect hinders realization of these devices in actual practice. Here we report on a giant Rashba-type spin splitting in two-dimensional electron systems that reside at tellurium-terminated surfaces of bismuth tellurohalides. Among these semiconductors, BiTeCl stands out for its isotropic metallic surface-state band with the Γ-point energy lying deep inside the bulk band gap. The giant spin splitting of this band ensures a substantial spin asymmetry of the inelastic mean free path of quasiparticles with different spin orientations.
自旋电子学旨在主动控制和操纵半导体器件中的自旋自由度。实现这一目标的一种很有前途的方法是利用可调谐的 Rashba 效应，该效应依赖于沉浸在非对称环境中的二维电子系统中的自旋轨道相互作用。自旋轨道诱导的二维电子态的自旋劈裂为许多理论上提出的自旋电子器件提供了基础。然而，缺乏具有大 Rashba 效应的半导体阻碍了这些器件在实际应用中的实现。在这里，我们报告了二维电子系统中存在的巨大 Rashba 型自旋劈裂，该二维电子系统位于铋碲卤化物的碲终止表面上。在这些半导体中，BiTeCl 因其各向同性的金属表面态能带而脱颖而出，Γ点能量位于体带隙深处。该能带的巨大自旋劈裂确保了具有不同自旋取向的准粒子的非弹性平均自由程的显著自旋不对称性。
