Based on first-principles calculations, we find novel valley-polarized quantum anomalous Hall (VP-QAH) phases with a large gap-0.19 eV at an appropriate buckled angle and tunable topological phase transitions driven by the spontaneous magnetization within a half-hydrogenated Bi honeycomb monolayer. Depending on the magnetization orientation, four different phases can emerge, i.e., two VP-QAH phases, ferromagnetic insulating and metallic states. When the magnetization is reversed from the +z to -z directions, accompanying with a sign change in the Chern number (from -1 to +1), the chiral edge state is moved from valley K to K′. Our findings provide a platform for designing dissipationless electronics and valleytronics in a more robust manner through the tuning of the magnetization orientation.
@article{arxiv.1412.1305,
title = {Valley-polarized quantum anomalous Hall phases and tunable topological phase transitions in half-hydrogenated Bi honeycomb monolayers},
author = {Cheng-Cheng Liu and Jin-Jian Zhou and Yugui Yao},
journal= {arXiv preprint arXiv:1412.1305},
year = {2015}
}