Exploring topological phase transition in Pt2Hg1−xTlxSe3

Abstract

The transition from trivial to non-trivial phase in two-dimensional materials are called a topological phase transition (TPT). The Berry phase, non-local string order parameter, and edge states define the topological nature of the system. A newly discovered jacutingaite ma- terial Pt₂HgSe₃ is a layered material which occurs naturally in the form of minerals. The material can be exfoliated and was predicted as a quantum spin Hall insulator. Here, on the basis of density functional theory and tight-binding calculations, we explore Pt₂Hg_1−xTl_xSe₃ (x = 0.25, 0.50, 0.75, 1) to understand the electronic and topological properties. We start with the parent material Pt₂HgSe₃ wherein Hg is replaced partially with x amount of Tl, to tune the topological phases. From the electronic structure calculations, Pt₂HgSe₃ is found to be a non-trivial semimetal in it’s bulk. Upon electron doping, the material transforms to strong topological metallic phase. The topological Z₂ invariant calculation shows TPT in Pt₂Hg₁−_xTl_xSe₃ with weak topological insulating state (0;001) for x=0, to strong topological metal (1;000) for x=1, respectively.