Topological phase diagrams of bulk and monolayer TiS2-x Tex.

With the use of ab initio calculations, the topological phase diagrams of bulk and monolayer TiS(2-x) Te(x) are established. Whereas bulk TiS(2-x) Te(x) shows two strong topological phases [1;(000)] and [1;(001)] for 0.44<x<0.56 and 0.56<x<1, respectively, the monolayer is topologically nontrivial for 0.48<x<0.80. Because in the latter doping range the topologically nontrivial nature survives down to a monolayer, TiS(2-x) Te(x) is a unique system for studying topological phases in three and two dimensions simultaneously.