Symmetry-breaking supercollisions in Landau-quantized graphene

TL;DR

This paper introduces a new defect-assisted relaxation mechanism in Landau-quantized graphene, explaining variable carrier relaxation times and offering a way to control these timescales through material quality.

Contribution

It proposes a symmetry-breaking defect-assisted supercollision mechanism that enables electron scattering with out-of-plane phonons, significantly affecting relaxation times.

Findings

Carrier relaxation times vary from picoseconds to nanoseconds.

Defect-assisted supercollisions accelerate carrier relaxation in low-quality samples.

Insights enable tuning of relaxation times in graphene and similar materials.

Abstract

Recent pump-probe experiments performed on graphene in a perpendicular magnetic field have revealed carrier relaxation times ranging from picoseconds to nanoseconds depending on the quality of the sample. To explain this surprising behavior, we propose a novel symmetry-breaking defect-assisted relaxation channel. This enables scattering of electrons with single out-of-plane phonons, which drastically accelerate the carrier scattering time in low-quality samples. The gained insights provide a strategy for tuning the carrier relaxation time in graphene and related materials by orders of magnitude.