We show the existence of massive Dirac fermions in electronic band structures of a few Fe atomic layers with perpendicular magnetization. Based on a tight binding model fitted to ab-initio band structure, we observe four distinct massive Dirac fermions near the Fermi level, which result from atomic spin-orbit coupling of Fe and a band inversion between Fe 4s-3dx2−y2 hybrid orbital band and 3dxy orbital band. These lead to a valence band with finite Chern integer (+2) and chiral edge modes near the Fermi level. When the chemical potential is set inside the Dirac gap by carrier doping, the Hall conductivity exhibits a plateau-like structure with quantized value 2he2, and orbital magnetization shows a prominent increase, latter of which is mostly due to chiral orbital motion of electrons along the edge modes. We discuss the stability of the Dirac fermions in Fe(001) monolayer on MgO(001) substrate and Fe(001) bilayer case.
@article{arxiv.1507.02382,
title = {Dirac fermions in Fe ultra-thin film},
author = {Xiao-Tian Zhang and Baolong Xu and Kohji Nakamura and Ryuichi Shindou},
journal= {arXiv preprint arXiv:1507.02382},
year = {2015}
}