Slowing hot carrier relaxation in graphene using a magnetic field

TL;DR

This study investigates how applying a magnetic field affects the ultrafast carrier relaxation processes in multi-layer graphene, revealing slowed relaxation due to suppressed electron-electron scattering.

Contribution

It demonstrates that a magnetic field can slow carrier relaxation in graphene by suppressing Auger scattering, a novel insight into controlling carrier dynamics.

Findings

Magnetic field reduces relaxation efficiency at low temperatures.

Two distinct relaxation times: ~50 fs and ~4 ps.

Suppression of Auger scattering due to Landau level spacing.

Abstract

A degenerate pump--probe technique is used to investigate the non equilibrium carrier dynamics in multi--layer graphene. Two distinctly different dynamics of the carrier relaxation are observed. A fast relaxation ($\sim 50$ fs) of the carriers after the initial effect of phase space filling followed by a slower relaxation ($\sim 4$ ps) due to thermalization. Both relaxation processes are less efficient when a magnetic field is applied at low temperatures which is attributed to the suppression of the electron-electron Auger scattering due to the non equidistant Landau level spacing of the Dirac fermions in graphene.