Strain-controlled evolution of electronic structure indicating topological phase transition in the quasi-one-dimensional superconductor TaSe3

Abstract

We report the signature of a strain-controlled topological phase transition in the electronic structure of a quasi-one-dimensional superconductor ${\mathrm{TaSe}}_{3}$. Using angle-resolved photoemission spectroscopy and first-principles calculation, ${\mathrm{TaSe}}_{3}$ is identified to be in a weak topological insulator phase which has topologically nontrivial surface states only at the allowed planes. Under uniaxial tensile strain, a Dirac point and the topological surface state emerge on the originally forbidden $(10\overline{1})$ plane, which demonstrates the transition to a strong topological insulator phase. Our results accomplish the experimental realization of possible topological insulating phases in ${\mathrm{TaSe}}_{3}$ and highlight the possibility of coupling the superconductivity with two distinct topological insulating phases in a controllable manner.