Stacking-dependent Electronic and Topological Properties in van der Waals Antiferromagnet MnBi$_2$Te$_4$ Films

TL;DR

This study combines first-principles calculations and tight-binding models to reveal how stacking variations in MnBi₂Te₄ films drastically alter their electronic and topological properties, including inducing topological phase transitions.

Contribution

It demonstrates the significant impact of stacking order on the topological phases of MnBi₂Te₄ and provides models and optical methods to distinguish different stacking configurations.

Findings

Lateral shifts induce topological phase transitions.

Incorrect stacking exhibits opposite topology to usual stacking.

Proposed optical setups differentiate stacking configurations.

Abstract

Combining first-principles calculations and tight-binding Hamiltonians, we study the stack-dependent behaviour of electronic and topological properties of layered antiferromagnet MnBi$_2$Te$_4$. Lateral shift of top septuple-layer greatly modify electronic properties, and even induce topological phase transition between quantum anomalous Hall (QAH) insulators with $C=1$ and trivial magnetic insulators with $C=0$. The local energy minimum of ``incorrect" stacking order exhibits thickness-dependent topology opposite to the usual stacking order, which is attribute to relatively weakened interlayer Te-Te interaction in ``incorrect" stacking configuration. Our effective model analysis provides a comprehensive understanding of the underlying mechanisms involved, and we also propose two optical setups that can effectively differentiate between different stacking configurations. Our findings underscores the nuanced and profound influence that interlayer sliding in magnetic topological materials can have on the macroscopic quantum states, opening new avenues for the design and engineering of topological quantum materials.