Quantum-metric-induced quantum Hall conductance inversion and reentrant transition in fractional Chern insulators

TL;DR

This paper reveals how the quantum metric influences the stability and topological properties of fractional Chern insulators, leading to conductance inversion and reentrant phase transitions driven by interaction effects.

Contribution

It uncovers the role of the quantum metric in causing deviations in Chern number and inducing phase transitions in fractional Chern insulators, a novel insight into their stability.

Findings

Quantum metric causes Chern number deviations in FCI states.

Variation in quantum metric induces band dispersion through interactions.

Reentrant transition from FCI to Fermi liquid with increasing interaction.

Abstract

The quantum metric of single-particle wave functions in topological flatbands plays a crucial role in determining the stability of fractional Chern insulating (FCI) states. Here, we unravel that the quantum metric causes the many-body Chern number of the FCI states to deviate sharply from the expected value associated with partial filling of the single-particle topological flatband. Furthermore, the variation of the quantum metric in momentum space induces band dispersion through interactions, affecting the stability of the FCI states. This causes a reentrant transition into the Fermi liquid from the FCI phase as the interaction strength increases.