Local manifestations of thickness dependent topology and axion edge state in topological magnet MnBi${}_2$Te${}_4$

Abstract

The interplay of non-trivial band topology and magnetism gives rise to a series of exotic quantum phenomena, such as the emergent quantum anomalous Hall (QAH) effect and topological magnetoelectric effect. Many of these quantum phenomena have local manifestations when the global symmetry is broken. Here, we report local signatures of the thickness dependent topology in intrinsic magnetic topological insulator MnBi${}_2$Te${}_4$(MBT), using scanning tunneling microscopy and spectroscopy on molecular beam epitaxy grown MBT thin films. A thickness-dependent band gap with an oscillatory feature is revealed, which we reproduce with theoretical calculations. Our theoretical results indicate a topological quantum phase transition beyond a film thickness of one monolayer, with alternating QAH and axion insulating states for even and odd layers, respectively. At an even-odd layer step, a localized gapped electronic state is observed, in agreement with an axion insulator edge state that results from a phase transition across the step. The demonstration of thickness-dependent topological properties highlights the role of nanoscale control over novel quantum states, reinforcing the necessity of thin film technology in quantum information science applications.

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• Generalized gradient approximation for solids and their surfaces
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• Mapping the Dirac fermions in intrinsic antiferromagnetic topological insulators (MnBi${}_2$Te${}_4$)(Bi${}_2$Te${}_3$)${}_n$ (n=0, 1)
• Realizing gapped surface states in magnetic topological insulator MnBi${}_{2-x}$Sb${}_x$Te${}_4$

Cited by in corpus (11)

• Observation of magnetism induced topological edge state in antiferromagnetic topological insulator MnBi4Te7
• Anti-site defect-induced disorder in compensated topological magnet MnBi${}_{2-x}$Sb${}_x$Te${}_4$
• Theory of the microwave impedance microscopy of Chern insulators
• Imaging the breakdown and restoration of topological protection in magnetic topological insulator MnBi${}_2$Te${}_4$
• High-fidelity dimer excitations using quantum hardware
• Shear-resistant topology in quasi one-dimensional van der Waals material Bi${}_4$Br${}_4$
• Surface Reconstructions in Thin-Films of Magnetic Topological Insulator MnBi${}_2$Te${}_4$
• Distributed Current Injection into a One-Dimensional Ballistic Edge Channel
• Light-driven topological and magnetic phase transitions in thin-layer antiferromagnets
• Defect-induced displacement of topological surface state in quantum magnet MnBi${}_2$Te${}_4$
• Procedures for assessing the stability of proposed topological materials