Valley-polarized quantum anomalous Hall phases and tunable topological phase transitions in half-hydrogenated Bi honeycomb monolayers

Abstract

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 $+\mathbf{z}$ to the $\ensuremath{-}\mathbf{z}$ directions, accompanied with a sign change in the Chern number (from $\ensuremath{-}1$ to +1), the chiral edge state is moved from valley $K$ to ${K}^{\ensuremath{'}}$. Our findings provide a platform for designing dissipationless electronics and valleytronics in a more robust manner through the tuning of the magnetization orientation.

Locations

• arXiv (Cornell University) - View - PDF
• DataCite API - View
• Physical Review B - View