Topological surface states of MnBi${}_2$Te${}_4$ at finite temperatures and at domain walls

Abstract

MnBi${}_2$Te${}_4$ has recently been the subject of intensive study, due to the prediction of axion insulator, Weyl semimetal, and quantum anomalous Hall insulator phases, depending on the structure and magnetic ordering. Experimental results have confirmed some aspects of this picture, but several experiments have seen zero-gap surfaces states at low temperature, in conflict with expectations. In this work, we develop a first-principles-based tight-binding model that allows for arbitrary control of the local spin direction and spin-orbit coupling, enabling us to accurately treat large unit-cells. Using this model, we examine the behavior of the topological surface state as a function of temperature, finding a gap closure only above the Néel temperature. In addition, we examine the effect of magnetic domains on the electronic structure, and we find that the domain wall zero-gap states extend over many unit-cells. These domain wall states can appear similar to the high temperature topological surface state when many domain sizes are averaged, potentially reconciling theoretical results with experiments.

6 pages main text, 7 supplemental

References in corpus (10)

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• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator
• Antiferromagnetic topological insulators
• Unfolding first-principles band structures
• Imaging Dirac-Mass Disorder from Magnetic Dopant-Atoms in the Ferromagnetic Topological Insulator Cr${}_x$(Bi${}_{0.1}$Sb${}_{0.9}$)${}_{2-x}$Te${}_3$
• Robust A-type order and spin-flop transition on the surface of the antiferromagnetic topological insulator MnBi${}_2$Te${}_4$
• Coexistence of Surface Ferromagnetism and Gapless Topological State in MnBi${}_2$Te${}_4$
• Magnetic imaging of antiferromagnetic domain walls

Cited by in corpus (8)

• Dissipationless Layertronics in Axion Insulator $\mathrm{MnB}{\mathrm{i}}_2\mathrm{T}{\mathrm{e}}_4$
• Strongly anisotropic spin dynamics in magnetic topological insulators
• Intrinsic magnetic topological insulators of the MnBi${}_2$Te${}_4$ family
• On the topological surface states of the intrinsic magnetic topological insulator Mn-Bi-Te family
• Spectral features of magnetic domain walls on surface of 3D topological insulators
• Imaging the breakdown and restoration of topological protection in magnetic topological insulator MnBi${}_2$Te${}_4$
• Reconstructing the wavefunction of magnetic topological insulators MnBi2Te4 and MnBi4Te7 using spin-resolved photoemission
• Accurate polymorphous description of the paramagnetic phases in MnBi${}_2$Te${}_4$