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arXiv · 1906.04510

Evidence for an axionic charge density wave in the Weyl semimetal (TaSe4)2I

Johannes Gooth·Barry Bradlyn·Shashank Honnali·Clemens Schindler·Nitesh Kumar·Jonathan Noky·Yangpeng Qi·Chandra Shekhar·Yan Sun·Zhijun Wang·Bogdan Andrei Bernevig·Claudia Felser
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Abstract

An axion insulator is a correlated topological phase, predicted to arise from the formation of a charge density wave in a Weyl semimetal. The accompanying sliding mode in the charge density wave phase, the phason, is an axion. It is expected to cause anomalous magneto-electric transport effects. However, this axionic charge density wave has so far eluded experimental detection. In this paper, we report the observation of a large, positive contribution to the magneto-conductance in the sliding mode of the charge density wave Weyl semimetal (TaSe4)2I for collinear electric and magnetic fields (E||B). The positive contribution to the magneto-conductance originates from the anomalous axionic contribution of the chiral anomaly to the phason current, and is locked to the parallel alignment of E and B. By rotating B, we show that the angular dependence of the magneto-conductance is consistent with the anomalous transport of an axionic charge density wave.

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Johannes Gooth, Barry Bradlyn, Shashank Honnali, Clemens Schindler, Nitesh Kumar, Jonathan Noky, Yangpeng Qi, Chandra Shekhar, Yan Sun, Zhijun Wang, Bogdan Andrei Bernevig, Claudia Felser. 2019-06-11. Evidence for an axionic charge density wave in the Weyl semimetal (TaSe4)2I. https://doi.org/10.1038/s41586-019-1630-4

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