Spin-density wave state in simple hexagonal graphite

TL;DR

This paper investigates the potential for spin-density wave order in AA graphite due to Fermi surface nesting, using mean-field theory to evaluate the instability caused by electron-electron interactions.

Contribution

It demonstrates that AA graphite's nested Fermi surface leads to a spin-density wave instability, providing a theoretical analysis of this phenomenon.

Findings

Fermi surface in AA graphite is well-nested.

Electron-electron interactions induce SDW instability.

Mean-field theory estimates SDW order parameter.

Abstract

Simple hexagonal graphite, also known as AA graphite, is a metastable configuration of graphite. Using tight-binding approximation it is easy to demonstrate that AA graphite is a metal with well-defined Fermi surface. The Fermi surface consists of two sheets, each shaped like a rugby ball. One sheet corresponds to electron states, another corresponds to hole states. The Fermi surface demonstrates good nesting: a suitable translation in the reciprocal space superposes one sheet onto another. In the presence of the electron-electron repulsion a nested Fermi surface is unstable with respect to spin-density wave ordering. This instability is studied using the mean-field theory at zero temperature, and the spin-density wave order parameter is evaluated.