A Chern insulator (quantum anomalous Hall insulator) phase is demonstrated to exist in a typical semi-Dirac system, the TiO2/VO2 heterostructure. By combining first-principles calculations with Wannier-based tight-binding model, we calculate the Berry curvature distribution, finding a Chern number of -2 for the valence bands, and demonstrate the existence of gapless chiral edge states, ensuring quantization of the Hall conductivity to 2e^2/h. A new semi-Dirac model, where each semi-Dirac cone is formed by merging three conventional Dirac points, is proposed to reveal how the nontrivial topology with finite Chern number is compatible with a semi-Dirac electronic spectrum.
@article{arxiv.1507.01742,
title = {Emergence of a Chern-insulating state from a semi-Dirac dispersion},
author = {Huaqing Huang and Zhirong Liu and Hongbin Zhang and Wenhui Duan and David Vanderbilt},
journal= {arXiv preprint arXiv:1507.01742},
year = {2015}
}