Nonequilibrium thermal state of a voltage-biased Mott insulator

Abstract

We establish the nonequilibrium thermal phases of a voltage driven antiferromagnetic Mott insulator in three dimensions, realized at steady state under a voltage bias. Starting from the Keldysh action for the half-filled Hubbard model, we derive an effective Langevin equation for the ``slow'' magnetic variables. The coupling of electrons to these degrees of freedom determine the transport properties. At low temperature we find a voltage-driven discontinuous insulator-metal transition, along with hysteresis. We map the suppression of the N\'eel temperature ${T}_{N}$ and pseudogap temperature ${T}_{\text{pg}}$ with increasing voltage, and discover that the biased Mott insulator has a finite temperature insulator-metal transition. The low temperature results resolve an experimental puzzle about hysteresis, and the thermal results make testable predictions on spectra and nonlinear transport.