Electronic compressibility of graphene: The case of vanishing electron correlations and the role of chirality

TL;DR

This paper explains why monolayer graphene's electronic compressibility is dominated by kinetic energy due to its linear dispersion and chirality, while bilayer graphene shows significant correlation effects.

Contribution

It provides a theoretical explanation for the differing roles of electron correlations in monolayer versus bilayer graphene based on their band structures.

Findings

Monolayer graphene's compressibility is governed by kinetic energy due to chirality.

Bilayer graphene shows restored electron correlation contributions.

Differences are due to the distinct low energy band structures.

Abstract

A recent surprising finding that electronic compressibility measured experimentally in monolayer graphene can be described solely in terms of the kinetic energy [J. Martin, et al., Nat. Phys. 4, 144 (2008)] is explained theoretically as a direct consequence of the linear energy dispersion and the chirality of massless Dirac electrons. For bilayer graphene we show that contributions to the compressibility from the electron correlations are restored. We attribute the difference to the respective momentum dependence of the low energy band structures of the two materials.