Electronic orbital angular momentum and magnetism of graphene

TL;DR

This paper calculates the orbital angular momentum of electrons in graphene under magnetic fields, linking it to magnetic properties and demonstrating how doping, electric fields, and quantum oscillations influence graphene's magnetism.

Contribution

It introduces a detailed calculation of electron orbital angular momentum in graphene and explores its impact on magnetism, including regulation by electric fields and comparison with Dirac fermions.

Findings

Magnetization decreases with carrier doping.

Large field magnetization exhibits plateaus and de Haas-van Alphen oscillations.

Electric fields can modulate graphene's magnetic properties.

Abstract

Orbital angular momentum (OAM) of graphene electrons in a perpendicular magnetic field is calculated and corresponding magnetic moment is used to investigate the magnetism of perfect graphene. Variation in magnetization demonstrates its decrease with carrier-doping, plateaus in a large field, and de Haas-van Alphen oscillation. Regulation of magnetism by a parallel electric field is presented. The OAM originates from atomic-scale electronic motion in graphene lattice, and vector hopping interaction between carbon atomic orbitals is the building element. A comparison between OAM of graphene electrons, OAM of Dirac fermions, and total angular momentum of the latter demonstrates their different roles in magnetism of graphene. Applicability and relation to experiments of the results are discussed.