Orbital Magnetic Field Driven Metal-Insulator Transition in Strongly Correlated Electron Systems

TL;DR

This paper investigates how strong orbital magnetic fields can induce a transition from insulator to metal in strongly correlated electron systems, using the Hubbard-Hofstadter model and dynamical mean field theory.

Contribution

It demonstrates that large magnetic fields can trigger a Mott insulator-to-metal transition, revealing the role of magnetic minibands and spectral weight redistribution in this process.

Findings

Magnetic fields induce insulator-to-metal transition in the model.

Kinetic energy increases due to magnetic miniband formation.

Results are relevant for experimental magnetic field-driven transitions.

Abstract

We study the effects of an orbital magnetic field on the Mott metal-insulator transition in the Hubbard-Hofstadter model. We demonstrate that sufficiently large magnetic fields induce a Mott insulator-to-metal phase transition supporting our claim with dynamical mean field theory (DMFT) numerical results. For both competing phases (metal and insulator) we observe a magnetic-fieldinduced metallization reflected in an enhancement of kinetic and potential energy. The kinetic energy of the Mott insulator increases due to the Aharonov-Bohm effect experienced by electrons virtually tunneling around an elementary plaquette which is, however, suppressed by strong correlations. The kinetic energy of the metallic phase, on the other hand, is more strongly affected by the magnetic field through a field-driven redistribution of spectral weight due to the formation of magnetic minibands. This leads to an increase of the kinetic energy which tends to stabilize the metallic state. Our theoretical results might be relevant for recent experimental studies on magnetic field driven insulator-to-metal transitions in strongly correlated materials such as VO2, $\lambda$-type organic conductors and moir\'e multilayers.