# Electric-field-induced Z2 topological phase transition in strained single bilayer Bi(111)

## TL;DR

This study uses first-principles calculations to explore how strain and electric fields induce topological phase transitions in single bilayer Bi(111), revealing potential for spintronic applications.

## Contribution

It demonstrates how strain influences the electric-field-induced topological phase transition in Bi(111) bilayers, identifying critical strains and transition behaviors.

## Key findings

- Quadratic band touching semimetal at 0.5% tensile strain
- Infinitesimal electric field switches topological phase near 0.5% strain
- Dirac cone positions vary with strain above and below 0.5%

## Abstract

For controlling the critical electric fields of the topological phase transition in single bilayer Bi(111), we investigated topological phases in a strained system through first-principles calculations. We found a quadratic band touching semimetallic state at tensile strain $\epsilon=0.5$%. Around this strain, the topological phase can be switched to a trivial insulator by an infinitesimal electric field. The positions at which Dirac cones appear in the electric-field-induced topological phase transition changed for the strain $\epsilon>0.5$% and $\epsilon<0.5$%. Our results indicate that this topological phase transition could be applied to novel spintronic devices.