Topological Gap Opening without Symmetry Breaking from Dynamical Quantum Correlations

TL;DR

This paper demonstrates that dynamical quantum fluctuations can induce a topological gap without symmetry breaking, revealing a novel transition mechanism distinct from traditional symmetry-breaking processes.

Contribution

It introduces a new mechanism for topological gap opening driven by quantum fluctuations, without symmetry breaking, in an interacting topological insulator model.

Findings

Dynamical quantum fluctuations can open a topological gap without symmetry breaking.

The transition changes from continuous to first-order with increasing interaction.

The transition exhibits Gross-Neveu critical behaviour near the endpoint.

Abstract

Topological phase transitions are typically associated with the formation of gapless states. Spontaneous symmetry breaking can lead to a gap opening thereby obliterating the topological nature of the system. Here we highlight a completely different destiny for a topological transition in presence of interaction. Solving a Bernevig-Hughes-Zhang model with local interaction, we show that dynamical quantum fluctuations can lead to the opening of a gap without any symmetry breaking. As we vary the interaction and the bare mass of the model, the continuous gapless topological transition turns into a first-order one, associated with the presence of massive Dirac fermion at the transition point showing a Gross-Neveu critical behaviour near the quantum critical endpoint. We identify the gap opening as a condensed matter analog of the Coleman-Weinberg mechanism of mass generation.