Influence of the Ge–Sb sublattice atomic composition on the topological electronic properties of Ge2Sb2Te5

We present ab initio calculations of an electronic structure and a topological invariant ν0 of the Ge2Sb2Te5 compound. We have found that in the case of equiatomic composition of Ge/Sb layers the Ge2Sb2Te5 compound is the topological insulator. The ν0 invariant does not depend on a specific location of Ge and Sb atoms in the mixed layers, and depends only on their concentration. The variation of the concentration in the Ge/Sb layers leads to a change of the topological invariant of the compound.