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.
@article{arxiv.1710.02657,
title = {Spin-density wave state in simple hexagonal graphite},
author = {K. S. Mosoyan and A. V. Rozhkov and A. O. Sboychakov and A. L. Rakhmanov},
journal= {arXiv preprint arXiv:1710.02657},
year = {2018}
}