Strain-controlled evolution of electronic structure indicating topological phase transition in the quasi-one-dimensional superconductor TaSe 3
In this work, we report the signature of a strain-controlled topological phase transition in the electronic structure of a quasione-dimensional superconductor TaSe 3 . Using angle-resolved photoemission spectroscopy and first-principles calculation, 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 TaSe 3 and highlight the possibility of coupling the superconductivity with two distinct topological insulating phases in a controllable manner.