Fan Xiaofeng, Singh David J, Zheng Weitao
College of Materials Science and Engineering, Jilin University , Changchun 130012, China.
Department of Physics and Astronomy, University of Missouri , Columbia, Missouri 65211-7010, United States.
J Phys Chem Lett. 2016 Jun 16;7(12):2175-81. doi: 10.1021/acs.jpclett.6b00693. Epub 2016 May 27.
Understanding the origin of valence band splitting is important because it governs the unique spin and valley physics in few-layer MoS2. We explore the effects of spin-orbit coupling and interlayer coupling on few-layer MoS2 using first-principles methods. We find spin-orbit coupling has a major contribution to the valence band splitting at K in multilayer MoS2. In double-layer MoS2, the interlayer coupling leads to the widening of the gap between the already spin-orbit split states. This is also the case for the bands of the K-point in bulk MoS2. In triple-layer MoS2, the strength of interlayer coupling of the spin-up channel becomes different from that of spin-down at K. This combined with spin-orbit coupling results in the band splitting in two main valence bands at K. With the increase of pressure, this phenomenon becomes more obvious with a decrease of main energy gap in the splitting valence bands at the K valley.
理解价带分裂的起源很重要，因为它决定了少层二硫化钼中独特的自旋和能谷物理性质。我们使用第一性原理方法探究了自旋轨道耦合和层间耦合对少层二硫化钼的影响。我们发现自旋轨道耦合对多层二硫化钼中K点的价带分裂有主要贡献。在双层二硫化钼中，层间耦合导致已经由自旋轨道分裂的态之间的能隙变宽。块状二硫化钼中K点的能带也是如此。在三层二硫化钼中，K点自旋向上通道的层间耦合强度与自旋向下的不同。这与自旋轨道耦合相结合，导致K点处两个主要价带的分裂。随着压力增加，这种现象变得更加明显，K谷分裂价带中的主能隙减小。
