Mesoscopic transport signatures of disorder-induced non-Hermitian phases

TL;DR

This paper explores how disorder-induced exceptional points in 2D Dirac semimetals affect quantum transport, revealing increased conductance at the Dirac point and anisotropic behavior linked to non-Hermitian spectral features.

Contribution

It demonstrates the influence of disorder-induced non-Hermitian phenomena on quantum transport and localization in 2D Dirac materials, supported by numerical simulations and potential experimental setups.

Findings

Disorder-induced EPs can increase conductance at the Dirac point.

Transport exhibits strong directional anisotropy linked to Fermi arcs.

Non-Hermitian spectral features influence localization properties.

Abstract

We investigate the impact on basic quantum transport properties of disorder-induced exceptional points (EPs) that emerge in a disorder-averaged Green's function description of two-dimensional (2D) Dirac semimetals with spin- or orbital-dependent potential scattering. Remarkably, we find that EPs may promote the nearly vanishing conductance of a finite sample at the Dirac point to a sizable value that increases with disorder strength. This striking behavior exhibits a strong directional anisotropy that is closely related to the Fermi arcs connecting the EPs. We corroborate our results by numerically exact simulations, thus revealing the fingerprints of characteristic non-Hermitian spectral features also on the localization properties of the considered systems. Finally, several candidates for the experimental verification of our theoretical analysis are discussed, including disordered electronic square-net materials and cold atoms in spin-dependent optical lattices.