Sensitivity of the electronic and topological properties of tetradymites upon atomic mutations

Abstract

The tetradymite compounds are known as good thermoelectric materials and also strong topological insulators, which exhibit unique electronic structures governed by several essential material features such as containing heavy elements and having small band gap. Here we demonstrate by first-principles calculations that for a given alloyed tetradymite, its topological nature actually shows certain sensitivity on the detailed atomic configurations, even if all of them have the same stoichiometric composition. Specifically, some tetradymites are found to be robust topological insulators (or normal insulators) upon arbitrary atomic mutations, which however can induce transition from topologically trivial to non-trivial or vice versa for other tetradymites. The underlying physical mechanisms are discussed in terms of the band gaps and strength of spin–orbit coupling in some exampling tetradymites.