Robust large-gap topological insulator phase in transition-metal chalcogenide ZrTe4Se

Based on density functional theory (DFT), we investigate the electronic properties of bulk and single-layer ZrTe4Se. The band structure of bulk ZrTe4Se 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 Z2 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 ZrTe4Se is a quantum spin Hall (QSH) insulator with a band gap 86.4 meV and Z2=1, the nontrivial metallic edge states further confirm the nontrivial topological nature. The maximum global band gap is 0.211 eV at 8% uniaxial tensile strain along the [100] direction. When the compressive strain is more than 1%, the band structure of single-layer ZrTe4Se 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.