Angular momentum anisotropy of Dirac carriers: A new twist in graphene

TL;DR

This paper explores the angular momentum properties of Dirac carriers in graphene, revealing how sublattice pseudospin and chirality influence angular momentum and related optical and magnetic properties.

Contribution

It introduces a microscopic perturbative model linking sublattice spin, winding number, and angular momentum in graphene, providing new insights into its electronic structure.

Findings

Angular momentum contributions vary with crystallographic direction.

The model predicts angular dependence of the g-factor.

Implications for light absorption in honeycomb structures.

Abstract

Dirac carriers in graphene are commonly characterized by a pseudospin degree of freedom, arising from the degeneracy of the two inequivalent sublattices. The inherent chirality of the quasiparticles leads to a topologically non-trivial band structure, where the in-plane component of sublattice spin and momentum are intertwined. Equivalently, sublattice imbalance is intimately connected with angular momentum, inducing a torque of opposite sign at each Dirac point. In this work we develop an intuitive picture that associates sublattice spin and winding number with angular momentum. We develop a microscopic perturbative model to obtain the finite angular momentum contributions along the main crystallographic directions. Our results can be employed to determine the angular dependence of the g-factor and of light absorption in honeycomb bipartite structures.