Coulomb interactions of massless Dirac fermions in graphene; pair-distribution functions and exchange-driven spin-polarized phases

TL;DR

This paper investigates how Coulomb interactions influence spin-polarized phases in graphene's massless Dirac fermions, revealing that correlations suppress spin polarization at high doping levels.

Contribution

It provides an analysis of exchange and correlation energies in graphene, showing that correlations prevent spin-polarized phases predicted by exchange energy alone.

Findings

Exchange energy favors spin polarization at high doping.

Correlation effects suppress spin-polarized phases.

Spin-polarized phases are unlikely in ideal graphene due to correlations.

Abstract

The quasi-2D electrons in graphene behave as massless fermions obeying a Dirac-Weyl equation in the low-energy regime near the two Fermi points. The stability of spin-polarized phases (SPP) in graphene is considered. The exchange energy is evaluated from the analytic pair-distribution functions, and the correlation energies are estimated via a closely similar four-component 2D electron fluid which has been investigated previously. SPPs appear for sufficiently high doping, when the exchange energy alone is considered. However, the inclusion of correlations is found to {\it suppress} the spin-phase transition in ideal graphene.