Nature of the Dirac gap modulation and surface magnetic interaction in axion antiferromagnetic topological insulator MnBi${}_2$Te${}_4$

Abstract

Modification of the gap at the Dirac point (DP) in antiferromagnetic (AFM) axion topological insulator MnBi${}_2$Te${}_4$ and its electronic and spin structure has been studied by angle- and spin-resolved photoemission spectroscopy (ARPES) under laser excitation with variation of temperature (9-35~K), light polarization and photon energy. We have distinguished both a large (62-67~meV) and a reduced (15-18~meV) gap at the DP in the ARPES dispersions, which remains open above the Néel temperature ($T_{\mathrm{N}}=24.5$~K). We propose that the gap above $T_{\mathrm{N}}$ remains open due to short-range magnetic field generated by chiral spin fluctuations. Spin-resolved ARPES, XMCD and circular dichroism ARPES measurements show a surface ferromagnetic ordering for large-gap sample and significantly reduced effective magnetic moment for the reduced-gap sample. These effects can be associated with a shift of the topological DC state towards the second Mn layer due to structural defects and mechanical disturbance, where it is influenced by a compensated effect of opposite magnetic moments.

References in corpus (31)

• Topological insulators and superconductors
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Topological Field Theory of Time-Reversal Invariant Insulators
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Seeing the magnetic monopole through the mirror of topological surface states
• Topological axion states in magnetic insulator MnBi${}_2$Te${}_4$ with the quantized magnetoelectric effect
• Experimental realization of an intrinsic magnetic topological insulator
• Unique thickness-dependent properties of the van der Waals interlayer antiferromagnet $\mathrm{MnB}{\mathrm{i}}_2\mathrm{T}{\mathrm{e}}_4$ films
• Magnetic impurities on the surface of a topological insulator
• Hedgehog Spin-texture and Berry's Phase tuning in a Magnetic Topological Insulator
• Chemical Aspects of the Antiferromagnetic Topological Insulator MnBi${}_2$Te${}_4$
• Highly-ordered wide bandgap materials for quantized anomalous Hall and magnetoelectric effects
• Skyrmion fractionalization and merons in chiral magnets with easy-plane anisotropy
• Quantized topological magnetoelectric effect of the zero-plateau quantum anomalous Hall state
• Gapless Dirac surface states in the antiferromagnetic topological insulator MnBi2Te4
• Surface states and Rashba-type spin polarization in antiferromagnetic MnBi${}_2$Te${}_4$
• Correlated Topological Insulators and the Fractional Magnetoelectric Effect
• Competing magnetic interactions in the antiferromagnetic topological insulator MnBi${}_2$Te${}_4$
• Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi${}_{1-x}$Mn${}_x{)}_2$Se${}_3$
• Witten effect in a crystalline topological insulator
• Dimensional Crossover Induced Topological Hall Effect in a Magnetic Topological Insulator
• Layer-by-layer entangled spin-orbital texture of the topological surface state in Bi2Se3
• Photoelectron spin-polarization-control in the topological insulator Bi2Se3
• New interpretation of the origin of 2DEG states at the surface of layered topological insulators
• Quantum anomalous vortex and Majorana zero mode in iron-based superconductor Fe(Te,Se)
• Filling of magnetic-impurity-induced gap in topological insulators by potential scattering
• Disorder enabled band structure engineering of a topological insulator surface
• Fractional angular momentum at topological insulator interfaces
• Josephson currents induced by the Witten effect
• Synchrotron radiation induced magnetization in magnetically-doped and pristine topological insulators
• Dirac point spectral weight suppression and surface "gaps" in nonmagnetic and magnetic topological insulators

Cited by in corpus (4)

• Topological magnetic materials of the (MnSb${}_2$Te${}_4$)$\cdot$(Sb${}_2$Te${}_3$)${}_n$ van der Waals compounds family
• Spin-polarized imaging of the antiferromagnetic structure and field-tunable bound states in kagome magnet FeSn
• Antiferromagnetic topological insulator with selectively gapped Dirac cones
• Intermediate anomalous Hall states induced by noncollinear spin structure in magnetic topological insulator MnBi2Te4