from intrinsic antiferromagnetic to ferromagnetic topological insulators*

Magnetic topological insulators provide an important materials platform to explore emergent quantum phenomena. Recently, MnBi₂Te₄ was discovered to be the first material realization of a van der Waals (vdW) antiferromagnetic topological insulator (TI). In the two-dimensional (2D) limit, at a record high temperature of 4.5 K, MnBi₂Te₄ manifests the QAH effect in the forced ferromagnetic state above 12 T [1]. To realize the QAH effect at lower fields or even zero field, it is essential to search for ferromagnetic TIs or antiferromagnetic TIs with lower saturation fields. By reducing the interlayer magnetic exchange interaction through our rational design of the natural heterostructure consisting of the building blocks of [MnBi₂Te₄] septuple layers and [Bi₂Te₃] quintuple layers, I will show that this family of materials can be tuned from antiferromagnetic to ferromagnetic, providing a superior material platform to investigate various emergent phenomena arising from the interplay between magnetism and band topology [2,3].
[1] Y. deng, et. al, arxiv: 1904.11468 (2019)
[2] C. H, et. al, arxiv: 1905.02154 (2019)
[3] C. H, et. al, arxiv: 1910.12847 (2019)