Liu Kai, Luo Wei, Ji Junyi, Barone Paolo, Picozzi Silvia, Xiang Hongjun
Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, 200433, China.
Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China.
Nat Commun. 2019 Nov 13;10(1):5144. doi: 10.1038/s41467-019-13197-z.
The Dresselhaus and Rashba effects are well-known phenomena in solid-state physics, in which spin-orbit coupling splits spin-up and spin-down energy bands of nonmagnetic non-centrosymmetric crystals. Here, we discuss a phenomenon we dub band splitting with vanishing spin polarizations (BSVSP), in which, as usual, spin-orbit coupling splits the energy bands in nonmagnetic non-centrosymmetric systems. Surprisingly, however, both split bands show no net spin polarization along certain high-symmetry lines in the Brillouin zone. In order to rationalize this phenomenon, we propose a classification of point groups into pseudo-polar and non-pseudo-polar groups. By means of first-principles simulations, we demonstrate that BSVSP can take place in both symmorphic (e.g., bulk GaAs) and non-symmorphic systems (e.g., two dimensional ferroelectric SnTe). Furthermore, we identify a linear magnetoelectric coupling in reciprocal space, which could be employed to tune the spin polarization with an external electric field. The BSVSP effect and its manipulation could therefore form the basis for future spintronic devices.
Dresselhaus效应和Rashba效应是固态物理学中众所周知的现象，其中自旋 - 轨道耦合会分裂非磁性非中心对称晶体的自旋向上和自旋向下能带。在此，我们讨论一种我们称之为“自旋极化消失时的能带分裂”（BSVSP）的现象，其中，与往常一样，自旋 - 轨道耦合会分裂非磁性非中心对称系统中的能带。然而，令人惊讶的是，在布里渊区的某些高对称线上，两个分裂能带都没有净自旋极化。为了合理解释这一现象，我们提出将点群分为伪极性群和非伪极性群。通过第一性原理模拟，我们证明BSVSP可以发生在对称型（例如体相GaAs）和非对称型系统（例如二维铁电体SnTe）中。此外，我们在倒易空间中识别出一种线性磁电耦合，它可用于通过外部电场调节自旋极化。因此，BSVSP效应及其操控可为未来的自旋电子器件奠定基础。
