Topological quantum transition driven by charge-phonon coupling in higher-order topological insulators

TL;DR

This paper explores how charge-phonon interactions can induce a topological phase transition in higher-order topological insulators, specifically in a modified Kane-Mele model, leading to a semimetal phase through band-gap closing.

Contribution

It demonstrates that electron-phonon coupling can drive a second-order topological insulator into a semimetal, revealing a new mechanism for topological phase transitions.

Findings

Electron-phonon interaction renormalizes system parameters.

Increasing coupling induces a transition to a semimetal phase.

Transition characterized by band-gap closing and topological invariant change.

Abstract

We investigate a second-order topological quantum transition of a modified Kane-Mele model driven by electron-phonon interaction. The results show that the system parameters of the bare modified Kane-Mele model are renormalized by the electron-phonon interaction. Starting from the second-order topological phase for the bare model, the increasing electron-phonon coupling strength can drive the second-order topological insulator into a semimetal phase. Such a secondorder topological phase transition is characterized by the band-gap closing, discontinuity of averaged ferminoic number and topological invariant.