1State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 2University of Chinese Academy of Sciences, Beijing 100049 3Beijing Academy of Quantum Information Sciences, Beijing 100193 4Beijing Computational Science Research Center, Beijing 100094
Abstract：Topological phase transition in a single material usually refers to transitions between a trivial band insulator and a topological Dirac phase, and the transition may also occur between different classes of topological Dirac phases. It is a fundamental challenge to realize quantum transition between $Z_{2}$ nontrivial topological insulator (TI) and topological crystalline insulator (TCI) in one material because $Z_{2}$ TI and TCI have different requirements on the number of band inversions. The $Z_{2}$ TIs must have an odd number of band inversions over all the time-reversal invariant momenta, whereas the newly discovered TCIs, as a distinct class of the topological Dirac materials protected by the underlying crystalline symmetry, owns an even number of band inversions. Taking PbSnTe$_{2}$ alloy as an example, here we demonstrate that the atomic-ordering is an effective way to tune the symmetry of the alloy so that we can electrically switch between TCI phase and $Z_{2}$ TI phase in a single material. Our results suggest that the atomic-ordering provides a new platform towards the realization of reversibly switching between different topological phases to explore novel applications.
2018, Vol. 35 
