Layer Zero-Line Modes in Antiferromagnetic Topological Insulators

TL;DR

This paper theoretically investigates layer-dependent zero-line modes in antiferromagnetic topological insulators MnBi$_2$Te$_4$, revealing how magnetic domain wall orientation influences their distribution across layers.

Contribution

It demonstrates the layer-dependent behavior of zero-line modes in MnBi$_2$Te$_4$ multilayers based on domain wall magnetization orientation, providing a new understanding of their manipulation.

Findings

ZLMs are evenly distributed in odd layers with out-of-plane magnetization.

In-plane magnetization allows ZLMs in even layers due to mirror-symmetry breaking.

Conductive channels are mainly in outermost layers as thickness increases.

Abstract

Recently, the magnetic domain walls have been experimentally observed in antiferromagnetic topological insulators MnBi$_2$Te$_4$, where we find that the topological zero-line modes (ZLMs) appear along the domain walls. Here, we theoretically demonstrate that these ZLMs are layer-dependent in MnBi$_2$Te$_4$ multilayers. For domain walls with out-of-plane ferromagnetism, we find that ZLMs are equally distributed in the odd-number layers. When domain walls possess in-plane magnetization, the ZLMs can also exist in even-number layers due to in-plane mirror-symmetry breaking. Moreover, the conductive channels are mainly distributed in the outermost layers with increasing layer thickness. Our findings lay out a strategy in manipulating ZLMs and also can be utilized to distinguish the corresponding magnetic structures.