Pressure driven Weyl-topological insulator phase transition in Weyl semimetal SrSi$_{2}$

Abstract

Using DFT-based first-principles calculations, we demonstrate the tuning of the electronic structure of Weyl semimetal SrSi$_{2}$ via external uniaxial strain. The uniaxial strain facilitates the opening of bandgap along $\Gamma$-X direction and subsequent band inversion between Si $p$ and Sr $d$ orbitals. Z$_{2}$ invariants and surface states reveal conclusively that SrSi$_{2}$ under uniaxial strain is a strong topological insulator. Hence, uniaxial strain drives the semimetallic SrSi$_{2}$ into fully gapped topological insulating state depicting a semimetal to topological insulator phase transition. Our results highlight the suitability of uniaxial strain to gain control over the topological phase transitions and topological states in SrSi$_{2}$.