Delocalization of 2D Dirac Fermions: the Role of a Broken Supersymmetry

TL;DR

This paper explores how a broken supersymmetry mechanism can lead to the delocalization of 2D Dirac fermions with random mass, revealing conditions under which fermions remain conductive despite strong localization effects.

Contribution

It introduces a superfield approach to demonstrate that spontaneous supersymmetry breaking causes fermion delocalization in a disordered 2D Dirac system.

Findings

A fermion component can delocalize due to supersymmetry breaking.

Delocalized fermions exhibit a non-singular density of states.

Supersymmetry is restored at large average random mass, with a critical boson component.

Abstract

The mechanism of delocalization of two-dimensional Dirac fermions with random mass is investigated, using a superfield representation. Although localization effects are very strong, one fermion component can delocalize due to the spontaneous breaking of a special supersymmetry of the model. The delocalized fermion has a non-singular density of states and is decribed by a diffusion propagator. Supersymmetry is restored if the mean of the random mass is sufficiently large. This is accompanied by a critical boson component.