Emergence of non-centrosymmetric topologicalinsulating phase in BiTeI under pressure

摘要

The spin–orbit interaction affects the electronic structure of solids in various ways. Topologicalinsulators are one example in which the spin–orbit interaction leads the bulk bands to havea non-trivial topology, observable as gapless surface or edge states. Another example is theRashba effect, which lifts the electron-spin degeneracy as a consequence of the spin–orbitinteraction under broken inversion symmetry. It is of particular importance to know how thesetwo effects, that is, the non-trivial topology of electronic states and the Rashba spin splitting,interplay with each other. Here we show through sophisticated first-principles calculations thatBiTeI, a giant bulk Rashba semiconductor, turns into a topological insulator under a reasonablepressure. This material is shown to exhibit several unique features, such as a highly pressuretunable giant Rashba spin splitting, an unusual pressure-induced quantum phase transition,and more importantly, the formation of strikingly different Dirac surface states at oppositesides of the material.