Issue 21, 2025

Electric control of Chern number in valley-polarized quantum anomalous Hall insulators

Abstract

The valley-polarized quantum anomalous Hall effect has attracted considerable interest in the condensed matter field due to the topologically protected edge states with a unique valley index. Here, using first-principles calculations, we demonstrate that the valley-polarized quantum anomalous Hall effect with a tunable Chern number can be realized in a Cr2COH monolayer through external electric fields. Our results show that the Cr2COH monolayer is a ferrovalley system with spontaneous valley polarization. Valley polarization originates from broken spatial inversion and time-reversal symmetries, giving rise to the anomalous valley Hall effect and the valley-polarized quantum anomalous Hall effect. Remarkably, an out-of-plane external electric field induces valley-contrasted Stark shifts, resulting in the energy gap closing and reopening in these valleys, thereby facilitating the manipulation of the Chern number from C = −1 to C = −3 in valley-polarized QAH insulators. Our findings provide a guide for designing quantum devices based on the valley-polarized quantum anomalous Hall effect.

Graphical abstract: Electric control of Chern number in valley-polarized quantum anomalous Hall insulators

Supplementary files

Article information

Article type
Paper
Submitted
05 Mar 2025
Accepted
15 Apr 2025
First published
16 Apr 2025

J. Mater. Chem. C, 2025,13, 10916-10923

Electric control of Chern number in valley-polarized quantum anomalous Hall insulators

X. Wang, Y. Liang and P. Zhao, J. Mater. Chem. C, 2025, 13, 10916 DOI: 10.1039/D5TC00976F

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