Intertwined Topological and Magnetic Orders in Atomically Thin Chern Insulator MnBi₂Te₄

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Manganese bismuth telluride (MnBi2Te4) is a van der Waals magnet with potential for Chern insulator physics.
• Its layered antiferromagnetic order suggests layer-dependent topological states.
• A magnetic field can induce a Chern insulator state in MnBi2Te4.

Purpose of the Study:

• To investigate the evolution of bulk electronic structure in MnBi2Te4 with tuning magnetic states.
• To understand the dependence of topological states on layer thickness.
• To establish a link between electronic structure, magnetic state, and topological order.

Main Methods:

• Utilized multimodal probes on atomically thin MnBi2Te4 devices.
• Continuously tuned the magnetic state of the material.
• Observed changes in bulk electronic structure and topological order.

Main Results:

• Established a one-to-one correspondence between electronic structure, magnetic state, topological order, and layer thickness.
• Observed a band crossing (bulk band gap closing and reopening) during the canted magnetic phase.
• Identified concurrent topological phase transitions in both even- and odd-layer-number devices.

Conclusions:

• The study reveals the intricate interplay between band topology and magnetic order in MnBi2Te4.
• Tuning the magnetic state drives topological phase transitions.
• Findings advance the understanding of novel topological magnets.