Optical absorption and carrier multiplication at graphene edges in a magnetic field

TL;DR

This paper investigates how magnetic fields influence optical absorption and carrier multiplication at graphene edges, revealing significant edge current amplification via impact ionization, with detailed analysis of different edge types and selection rules.

Contribution

It provides new insights into optical absorption and carrier multiplication mechanisms at graphene edges under magnetic fields, including exact and approximate selection rules and decay rate dependencies.

Findings

Magnetic fields bend particle trajectories, generating directed edge currents.

Impact ionization significantly amplifies edge currents.

Different edge types exhibit distinct absorption and multiplication behaviors.

Abstract

We study optical absorption at graphene edges in a transversal magnetic field. The magnetic field bends the trajectories of particle- and hole excitations into antipodal direction which generates a directed current. We find a rather strong amplification of the edge current by impact ionization processes. More concretely, the primary absorption and the subsequent carrier multiplication is analyzed for a graphene fold and a zigzag edge. We identify exact and approximate selection rules and discuss the dependence of the decay rates on the initial state.