Floquet band engineering and topological phase transitions in 1T' transition metal dichalcogenides

TL;DR

This paper explores how circularly polarized light can induce topological phase transitions in 1T' transition metal dichalcogenide monolayers, revealing potential for light-controlled topological states.

Contribution

It provides first-principles calculations showing light-induced topological phase transitions in 1T' MX2 monolayers, including transitions from QSH to QAH and trivial phases.

Findings

Te-based MX2 transitions from QSH semimetal to QSH insulator with a 92.5 meV gap

Se- and S-based MX2 transition from QSH to QAH and trivial phases

Light intensity controls topological phase transitions

Abstract

Using ab initio tight-binding approaches, we investigate Floquet band engineering of the 1T' phase of transition metal dichalcogenides (MX2, M = W, Mo and X = Te, Se, S) monolayers under the irradiation with circularly polarized light. Our first principles calculations demonstrate that light can induce important transitions in the topological phases of this emerging materials family. For example, upon irradiation, Te-based MX2 undergoes a phase transition from quantum spin Hall (QSH) semimetal to time-reversal symmetry broken QSH insulator with a nontrivial band gap of up to 92.5 meV. On the other hand, Se- and S-based MX2 undergoes the topological phase transition from the QSH effect to the quantum anomalous Hall (QAH) effect and into trivial phases with increasing light intensity. From a general perspective, our work brings further insight into non-equilibrium topological systems.