Year: 2026
Type: article
Abstract: A widespread experimental realization of quantized anomalous transport in the intrinsic magnetic topological insulator MnBi_{2}Te_{4} is hindered by its elusive surface magnetic gap. Uncovering the origin of the gapless states is thus essential for accessing its topological properties. Here, we show that surface defects lower the electrostatic potential, drive topological surface states into subsurface layers, and suppress exchange interactions, thereby closing the gap. Tuning the surface electrostatic potential via external electric fields or interfacial fields in van der Waals heterostructures restores the expected gap and enables control of its topology. This is confirmed by model calculations and validated in defective MnBi_{2}Te_{4} films interfaced with polar insulators, explaining the enhanced quantum anomalous Hall effect under AlO_{x} capping observed in recent experiments. Our theory identifies electrostatically driven surface-state delocalization as a competitive origin of gap suppression and proposes displacement-field engineering for robust quantized transport.
Source: Physical Review Letters
DOI: 10.1103/xz7k-zd8c
Authors: Ce Bian, Hengxin Tan, Wenhui Duan
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Natural Science Foundation of China, Ministry of Education of the People's Republic of China, Science and Technology Commission of Shanghai Municipality, Renmin University of China, Beijing Innovation Center for Future Chip, National Science and Technology Major Project, National Key Research and Development Program of China
OpenAlex ID: W7213969233