Mean-field results on the Anderson impurity model out of equilibrium

TL;DR

This paper explores the phase diagram of the Anderson impurity model under non-equilibrium conditions using a mean-field approach, revealing how contact asymmetry stabilizes magnetic phases at high voltages.

Contribution

It extends the unrestricted Hartree-Fock method to non-equilibrium, providing an analytic phase boundary and analyzing the effects of contact asymmetry on magnetic stability.

Findings

Exact analytic phase boundary in symmetric case

Asymmetry prevents magnetic suppression at high voltages

Magnetic regime persists regardless of voltage with contact asymmetry

Abstract

We investigate the mean-field phase diagram of the Anderson impurity model out of equilibrium. Generalising the unrestricted Hartree-Fock approach to the non-equilibrium situation we derive and analyse the system of equations defining the critical surface separating the magnetic regime from the non-magnetic one. An exact analytic solution for the phase boundary as a function of the applied voltage is found in the symmetric case. Surprisingly, we find that as soon as there is an asymmetry, even small, between the contacts, no finite voltage is able to destroy the magnetic regime which persists at arbitrary high voltages.