Prediction of band inversion in Janus In2XYZ (X, Y, and Z = S, Se, Te) monolayers.

Abstract

In this work, the electronic and spin characteristics of Janus In2X2Y and In2XYZ (X, Y, and Z = S, Se, Te) monolayers are explored. The two sides of these Janus compounds have distinct vacuum levels due to their vertical asymmetry, which causes different work functions. An emerging dipole moment alters the band alignments on both surfaces of the Janus In2X2Y structures due to electronegativity differences between various chalcogen atoms on each surface. The band structures of these monolayers with and without spin-orbit coupling (SOC) are compared. The SOC consideration opens a finite bandgap in the In2STeS, In2SSTe, In2SeTeSe, and In2SeTeTe monolayers, while demonstrating a metallic behavior without SOC. The band inversion is indicated in these monolayers using projected band structures. In addition, In2SSeTe and In2SeTeS monolayers exhibit band inversion, and In2SeTeS has the highest topological bandgap as 111 meV.