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arXiv · 2005.14074

Using nonlocal surface transport to identify the axion insulator

Rui Chen·Shuai Li·Hai-Peng Sun·Qihang Liu·Yue Zhao·Hai-Zhou Lu·X. C. Xie
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Abstract

The axion is a hypothetical but experimentally undetected particle. Recently, the antiferromagnetic topological insulator MnBi$_2$Te$_4$ has been predicted to host the axion insulator, but the experimental evidence remains elusive. Specifically, the axion insulator is believed to carry "half-quantized" chiral currents running antiparallel on its top and bottom surfaces. However, it is challenging to measure precisely the half-quantization. Here, we propose a nonlocal surface transport device, in which the axion insulator can be distinguished from normal insulators without a precise measurement of the half-quantization. More importantly, we show that the nonlocal surface transport, as a qualitative measurement, is robust in realistic situations when the gapless side surfaces and disorder come to play. Moreover, thick electrodes can be used in the device of MnBi$_2$Te$_4$ thick films, enhancing the feasibility of the surface measurements. This proposal will be insightful for the search of the axion insulator and axion in topological matter.

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Rui Chen, Shuai Li, Hai-Peng Sun, Qihang Liu, Yue Zhao, Hai-Zhou Lu, X. C. Xie. 2020-05-28. Using nonlocal surface transport to identify the axion insulator. https://doi.org/10.1103/physrevb.103.l241409

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