Evolution of the Electronic Structure of Ultrathin MnBi 2 Te 4 Films

作者：Runzhe Xu, Yunhe Bai, J. S. Zhou, Jiaheng Li, Xu Gu, Na Qin, Zhongxu Yin, Xian Du, Qinqin Zhang, Wenxuan Zhao, Yidian Li, Yang Wu, Cui Ding, Lili Wang, Aiji Liang, Zhongkai Liu, Yong Xu, Xiao Feng, Ke He, Yulin Chen, Lexian Yang · 发表于：Nano Letters · 年份：2022 · DOI：10.1021/acs.nanolett.2c02034 · 被引用次数：22 · 研究领域：Topological Materials and Phenomena、2D Materials and Applications、Advanced Condensed Matter Physics

Ultrathin films of intrinsic magnetic topological insulator MnBi 2 Te 4 exhibit fascinating quantum properties such as the quantum anomalous Hall effect and the axion insulator state. In this work, we systematically investigate the evolution of the electronic structure of MnBi 2 Te 4 thin films. With increasing film thickness, the electronic structure changes from an insulator type with a large energy gap to one with in-gap topological surface states, which is, however, still in drastic contrast to the bulk material. By surface doping of alkali-metal atoms, a Rashba split band gradually emerges and hybridizes with topological surface states, which not only reconciles the puzzling difference between the electronic structures of the bulk and thin-film MnBi 2 Te 4 but also provides an interesting platform to establish Rashba ferromagnet that is attractive for (quantum) anomalous Hall effect. Our results provide important insights into the understanding and engineering of the intriguing quantum properties of MnBi 2 Te 4 thin films.