Any Axion Insulator Must be a Bulk Three-Dimensional Topological Insulator

Fijalkowski, K. M.; Liu, N.; Hartl, M.; Winnerlein, M.; Mandal, P.; Coschizza, A.; Fothergill, A.; Grauer, S.; Schreyeck, S.; Brunner, K.; Greiter, M.; Thomale, R.; Gould, C.; Molenkamp, L. W.

doi:10.48550/arxiv.2105.09608

Cited by 1 publication

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References 44 publications

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“…While quantized Hall conductance could be taken as a direct evidence of QAH phase, it is far from conclusive to identify axion insulator phase based on the observation of zero Hall plateau in transport [30][31][32]. That's because charge transport is a global measurement of the entire device which can be complicated by the emergence of multidomain states and the existence of parallel trivial conducting channels.…”

Section: Exploredmentioning

confidence: 99%

Direct visualization of edge state in even-layer MnBi2Te4 at zero magnetic field

Lin

Feng

Wang

et al. 2021

Preprint

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Being the first intrinsic antiferromagnetic (AFM) topological insulator, MnBi2Te4 is argued to be a topological axion state in its even-layer form due to the antiparallel magnetization between the top and bottom layers. Here we combine both transport and scanning microwave impedance microscopy (sMIM) to investigate such axion state in atomically thin MnBi2Te4 with even-layer thickness at zero magnetic field. While transport measurements show a zero Hall plateau signaturing the axion state, sMIM uncovers an unexpected edge state raising questions regarding the nature of the “axion state”. Based on our model calculation, we propose that the even-layer MnBi2Te4 at zero field is in an AFM quantum spin Hall (QSH) state hosting a pair of helical edge states. Such novel AFM QSH is originated from the combination of half translation symmetry and time-reversal symmetry in MnBi2Te4. Our finding thus signifies the richness of topological phases in MnB2Te4 that has yet to be fully explored.

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Section: Exploredmentioning

confidence: 99%