Topological phases in the TaSe3 compound

TL;DR

This paper uses first-principles calculations to identify TaSe3 as a 3D strong topological insulator with a stable topological phase that coexists with superconductivity, making it ideal for studying topological-superconducting interplay.

Contribution

It demonstrates that TaSe3 is a stable 3D topological insulator with various topological phases under strain, and highlights its potential for experimental exploration of topological and superconducting phase interactions.

Findings

TaSe3 is a 3D strong topological insulator with a single Dirac cone surface state.

Strain can induce various topological phases, including weak TI and Dirac semimetal.

TaSe3's coexistence of topological and superconducting phases offers a platform for future studies.

Abstract

Based on first-principles calculations, we show that stoichiometric TaSe3, synthesized in space group P21/m, belongs to a three-dimensional (3D) strong topological insulator (TI) phase with Z2 invariants (1;100). The calculated surface spectrum shows clearly a single Dirac cone on surfaces, with helical spin texture at a constant energy contour. To check the stability of the topological phase, strain effects have been systematically investigated, showing that many topological phases survive in a wide range of the strains along both the a- and c-axes, such as strong TI (STI), weak TI (WTI) and Dirac semimetal phases. TaSe3 provides us an ideal platform for experimental study of topological phase transitions. More interestingly, since superconductivity in TaSe3 has been reported for a long time, the co-existence of topological phases and superconducting phase suggests that TaSe3 is a realistic system to study the interplay between topological and superconducting phases in the future.