Sublattice effect on topological surface states in complex (SnTe)n>1(Bi2Te3)m=1 compounds

An exotic type of topological spin-helical surface state was found in layered van der Waals bonded (SnTe)n=2,3(Bi2Te3)m=1 compounds which comprise two covalently bonded band inverted sublattices, SnTe and Bi2Te3, within a building block. This topological state demonstrates unusual dispersion within the band gap. The dispersion of the surface state has two linear sections of different slope with a shoulder feature between them. Such a dispersion of the topological surface state enables an effective switch of the velocity of topological carriers by means of applying an external electric field