Visualizing the interplay of Dirac mass gap and magnetism at nanoscale in intrinsic magnetic topological insulators

Abstract

In intrinsic magnetic topological insulators, Dirac surface state gaps are prerequisites for quantum anomalous Hall and axion insulating states. Unambiguous experimental identification of these gaps has proved to be a challenge, however. Here we use molecular beam epitaxy to grow intrinsic MnBi2Te4 thin films. Using scanning tunneling microscopy/spectroscopy, we directly visualize the Dirac mass gap and its disappearance below and above the magnetic order temperature. We further reveal the interplay of Dirac mass gaps and local magnetic defects. We find that in high defect regions, the Dirac mass gap collapses. Ab initio and coupled Dirac cone model calculations provide insight into the microscopic origin of the correlation between defect density and spatial gap variations. This work provides unambiguous identification of the Dirac mass gap in MnBi2Te4, and by revealing the microscopic origin of its gap variation, establishes a material design principle for realizing exotic states in intrinsic magnetic topological insulators.

arXiv commentMain and SI

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Cited by in corpus (14)

• Distinct magnetic gaps between antiferromagnetic and ferromagnetic orders driven by surface defects in the topological magnet MnBi2Te4
• Dissipationless Layertronics in Axion Insulator $\mathrm{MnB}{\mathrm{i}}_2\mathrm{T}{\mathrm{e}}_4$
• Intrinsic magnetic topological insulators of the MnBi${}_2$Te${}_4$ family
• Ubiquitous order-disorder transition in the Mn antisite sublattice of the (MnBi${}_2$Te${}_4$)(Bi${}_2$Te${}_3$)${}_n$ magnetic topological insulators
• Ferroelectrically switchable magnetic multistates in MnBi${}_2$Te${}_4$(Bi${}_2$Te${}_3$)${}_n$ and MnSb${}_2$Te${}_4$(Sb${}_2$Te${}_3$)${}_n$ (n = 0, 1) thin films
• Anti-site defect-induced disorder in compensated topological magnet MnBi${}_{2-x}$Sb${}_x$Te${}_4$
• Role of Magnetic Defects and Defect-engineering of Magnetic Topological Insulators
• Magnetic warping in topological insulators
• Imaging the breakdown and restoration of topological protection in magnetic topological insulator MnBi${}_2$Te${}_4$
• Frequency-dependent Faraday and Kerr rotation in anisotropic nonsymmorphic Dirac semimetals
• Robust Majorana bound states in magnetic topological insulator nanoribbons with fragile chiral edge channels
• Reconstructing the wavefunction of magnetic topological insulators MnBi2Te4 and MnBi4Te7 using spin-resolved photoemission
• Fate of surface gaps in magnetic topological insulators
• Defect-induced displacement of topological surface state in quantum magnet MnBi${}_2$Te${}_4$