Fig. 7: Band inversion due to spin–orbit coupling.
Band structure of a Bi and b Sb. In Bi, the gap between conduction and valence bands at the L-point is small and the hierarchy between them is inverted from the ordinary hierarchy under the Peierls transition. The upper band is the symmetric Ls and the lower is the antisymmetric La. c The Brillouin zone and its high-symmetry points. d, e Energies of Ls and La as a function of the magnitude of SOC for Bi and Sb. The effective λ for Bi and Sb yielding the best fit to experiment are mentioned in Table 2. The energy hierarchy Ls/La is altered by SOC in Bi, whereas it is not in Sb. All these calculations were carried out by using the Liu-Allen’s tight-binding model6.
