Robust large-gap topological insulator phase in transition-metal chalcogenide ZrTe$_4$Se

TL;DR

This study uses density functional theory to reveal that ZrTe$_4$Se exhibits a strain-tunable topological insulator phase with a large band gap, suitable for nanoelectronic applications.

Contribution

It demonstrates that ZrTe$_4$Se$ can be a large-gap topological insulator with strain-induced phase transitions, expanding the material options for topological electronics.

Findings

Bulk ZrTe$_4$Se is a weak topological insulator with a maximum band gap of 0.189 eV.

Single-layer ZrTe$_4$Se is a quantum spin Hall insulator with a band gap of 86.4 meV.

Strain can induce a transition between topological insulator and semimetal phases.

Abstract

Based on density functional theory (DFT), we investigate the electronic properties of bulk and single-layer ZrTe$_4$Se. The band structure of bulk ZrTe$_4$Se can produce a semimetal-to-topological insulator (TI) phase transition under uniaxial strain. The maximum global band gap is 0.189 eV at the 7\% tensile strain. Meanwhile, the Z$_2$ invariants (0; 110) demonstrate conclusively it is a weak topological insulator (WTI). The two Dirac cones for the (001) surface further confirm the nontrivial topological nature. The single-layer ZrTe$_4$Se is a quantum spin Hall (QSH) insulator with a band gap 86.4 meV and Z$_2$=1, the nontrivial metallic edge states further confirm the nontrivial topological nature. The maximum global band gap is 0.211 eV at the tensile strain 8\%. When the compressive strain is more than 1\%, the band structure of single-layer ZrTe$_4$Se produces a TI-to-semimetal transition. These theoretical analysis may provide a method for searching large band gap TIs and platform for topological nanoelectronic device applications.