Topological insulating in GeTe/Sb ₂Te ₃ phase-change superlattice

GeTe/Sb ₂Te ₃ superlattice phase-change memory devices demonstrated greatly improved performance over that of Ge ₂Sb ₂Te ₅, a prototype record media for phase-change random access memory. In this work, we show that this type of GeTe/Sb ₂Te ₃ superlattice exhibits topological insulating behavior on the basis of abinitio calculations. The analysis of the band structures and parities as well as Z ₂ topological invariants unravels the topological insulating nature in these artificial materials. Furthermore, the topological insulating character remains in the GeTe/Sb ₂Te ₃ superlattice under small compressive strains, whereas it is not observed as more Sb ₂Te ₃ building blocks introduced in the superlattice. The present results show that multifunctional data storages may be achieved in the GeTe/Sb ₂Te ₃ superlattice. Such kinds of artificial materials can be used in phase-change random access memory, spintronics, and quantum computing.