Topological Phase Diagrams of Bulk and Monolayer TiS2-xTex

With the use of ab initio calculations, the topological phase diagrams of bulk and monolayer TiS2-xTex are established. Whereas bulk TiS2-xTex 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, TiS2-xTex is a unique system for studying topological phases in three and two dimensions simultaneously. DOI: 10.1103/PhysRevLett.110.077202