The rising of topological materials MnBi₂Te₄/(Bi₂Te₃)_n with built-in magnetization provides a great platform for the realization of both Chern-insulator and axion-insulator phases, manifesting integer and half-integer quantum anomalous Hall (QAH) effects, respectively [1-3]. Using both model Hamiltonian and first-principles calculations, we demonstrate that rich 2D and 3D topological phase diagrams can be established with the mapping of MnBi₂Te₄/(Bi₂Te₃)_n systems. For the 2D topological phases, we provide design principles to trigger integer QAH states by tuning experimentally accessible knobs, such as slab thickness and magnetization [2]. For the 3D topological phases, we find that the surface anomalous Hall conductivity in the axion-insulator phase is a well-localized hanging around e²/2h, depending on the magnetic homogeneity [3]. We then discuss the preconditions and several experimental proposals to reveal the surface anomalous Hall effect in MnBi₂Te₄/(Bi₂Te₃)_n. Finally, some experimental progresses and theoretical insights on the issue of the surface gaps in MnBi₂Te₄/(Bi₂Te₃)_n is discussed (if time permits) [4-7].

References

[1] C. Hu et al. Nat. Commun. 11, 97 (2020).

[2] H. Sun et al. Phys. Rev. Lett. 123, 096401 (2019).

[3] M. Gu et al. arXiv:2005.13943 (2020).

[4] Y. Hao et al. Phys. Rev. X 9, 041038 (2019).

[5] X. Wu et al. Phys. Rev. X 9, 041038 (2020).

[6] X. Ma et al. arXiv:2004.09123 (2020).

[7] R. Lu et al. arXiv:2009.04140 (2020).

刘奇航，南方科技大学副教授，本科及博士均毕业于北京大学物理学院，曾任美国西北大学博士后、美国科罗拉多大学博尔德分校助理研究员；主要从事以密度泛函理论为主的凝聚态理论研究，研究兴趣包括理解材料中新奇的电学，磁学，光学，缺陷，自旋极化，拓扑等物性，以及功能导向的新型材料设计及预测。工作期间以主要作者身份已发表包括Nat. Phys.、Nat. Commun.、Phys. Rev. X、Phys, Rev. Lett.、Nano Lett.、JACS等多篇学术论文；署名作者共计已发表学术论文60余篇，Google Scholar统计引用超过3700次；2018年入选“国家特聘青年专家”。