Layer-dependent zero-line modes in antiferromagnetic topological insulators

Abstract

Recently, the magnetic domain walls have been experimentally observed in antiferromagnetic topological insulators ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$. Here we study the intrinsic topological zero-line modes (ZLMs) that appear along the domain walls, and find that these ZLMs are layer dependent in ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$ multilayers. We reveal the role of the spatial layer degree of freedom and magnetic domain wall configurations in determining the electronic transport properties and the distribution of the ZLMs in antiferromagnetic topological insulator systems. For antiferromagnetic domain wall with out-of-plane magnetization within each domain, we find that ZLMs are only distributed in the odd-number layers equally. For the N\'eel domain wall, the ZLMs are no longer distributed in the odd-number layers equally due to the mirror symmetry $({M}_{z})$ breaking, and can exist in the even-number layers in multilayer systems. Moreover, the ZLMs are mainly distributed in the outermost layers with increasing layer thickness. Our findings lay out a strategy in manipulating ZLMs and can be utilized to distinguish the corresponding magnetic structures.