Diamagnetic Persistent Currents and Spontaneous Time-Reversal Symmetry Breaking in Mesoscopic Structures

TL;DR

This paper explores new strongly interacting phases in mesoscopic systems, revealing diamagnetic persistent currents and spontaneous time-reversal symmetry breaking, advancing understanding of quantum coherence and interactions in mesoscopic physics.

Contribution

It demonstrates the existence of diamagnetic persistent currents and spontaneous time-reversal symmetry breaking in mesoscopic structures with strong interactions and chaotic scattering.

Findings

Diamagnetic persistent currents observed for even angular momentum channels.

Spontaneous breaking of time-reversal symmetry in odd angular momentum channels.

Transition driven by coupling to dissipative leads.

Abstract

Recently, new strongly interacting phases have been uncovered in mesoscopic systems with chaotic scattering at the boundaries by two of the present authors and R. Shankar. This analysis is reliable when the dimensionless conductance of the system is large, and is nonperturbative in both disorder and interactions. The new phases are the mesoscopic analogue of spontaneous distortions of the Fermi surface induced by interactions in bulk systems and can occur in any Fermi liquid channel with angular momentum $m$. Here we show that the phase with $m$ even has a diamagnetic persistent current (seen experimentally but mysterious theoretically), while that with $m$ odd can be driven through a transition which spontaneously breaks time-reversal symmetry by increasing the coupling to dissipative leads.