Asymmetric Electron Energy Loss in Drift-Current Biased Graphene

TL;DR

This paper investigates how a drift current bias in graphene causes asymmetric energy loss in passing electron beams, revealing nonreciprocal effects and potential for testing theoretical models via electron spectroscopy.

Contribution

It demonstrates the impact of drift bias on electron energy loss spectra in graphene and proposes using electron beam spectroscopy to validate different conductivity models.

Findings

Energy loss spectrum becomes asymmetric with drift bias.

Opposite drift and electron velocities boost energy loss.

Spectroscopy can distinguish between theoretical models.

Abstract

The electric drift current bias was recently introduced as a new paradigm to break the Lorentz reciprocity in graphene. Here, we study the impact of the nonreciprocal response in the energy extracted from a beam of swift charges travelling in the vicinity a graphene sheet with drifting electrons. It is demonstrated that the drift bias leads to an asymmetric electron-energy-loss spectrum that depends on the sign of the charges velocity. It is found that when the drift and electron beam velocities have comparable values but opposite signs, the energy loss is boosted resulting in a noncontact friction-type effect. In contrast, when the drift and electron beam velocities have the same sign the energy loss is negligible. Furthermore, it is shown that different theoretical models of the drift-biased graphene conductivity yield distinct peaks for the energy-loss spectrum, and thereby electron beam spectroscopy can be used to test the validity of the different theories.