Breathing-Driven Metal-Insulator Transition in Correlated Kagome Systems

TL;DR

This study investigates how the breathing effect influences the metal-insulator transition in correlated kagome systems, revealing that it can be used to control electronic and magnetic properties.

Contribution

We demonstrate that the breathing effect, combined with electron interactions, induces a metal-insulator transition and alters magnetic phases in kagome lattice models.

Findings

Breathing strength affects the average sign problem in quantum Monte Carlo simulations.

The critical interaction strength for metal-insulator transition depends on the breathing effect.

The phase diagram shows a transition from paramagnetic metal to Mott insulator with increasing interaction.

Abstract

Inspired by the recent discovery of breathing kagome materials \(\rm Nb_3Cl_8\) and \(\rm Nb_3TeCl_7\), we have explored the influence of the breathing effect on the Hubbard model of the kagome lattice. Utilizing the determinant quantum Monte Carlo method, we first investigated the average sign problem in the breathing kagome lattice, which is significantly affected by both the breathing strength and the interaction strength. Secondly, we calculated the electronic kinetic energy, the direct current conductivity, and the electronic density of states at the Fermi level to determine the critical interaction strength for the metal-insulator transition. Our results indicate that the breathing effect, in conjunction with the interaction strength, drives the kagome system from a metal to an insulator. Finally, we evaluated the magnetic properties and constructed a phase diagram incorporating both transport and magnetic properties. The phase diagram reveals that as the interaction strength increases, the system transitions from a paramagnetic metal to a Mott insulator. Our research provides a theoretical guidance for utilizing the breathing effect to control the band gaps, conductivity, and magnetic properties of kagome materials with electronic interactions.