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arXiv · 2006.14713

Observation of Weyl fermions in a magnetic non-centrosymmetric crystal

Daniel S. Sanchez·Guoqing Chang·Ilya Belopolski·Hong Lu·Jia-Xin Yin·Nasser Alidoust·Xitong Xu·Tyler A. Cochran·Xiao Zhang·Yi Bian·Songtian S. Zhang·Yi-Yuan Liu·Jie Ma·Guang Bian·Hsin Lin·Su-Yang Xu·Shuang Jia·M. Zahid Hasan
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Abstract

Characterized by the absence of inversion symmetry, non-centrosymmetric materials are of great interest because they exhibit ferroelectricity, second harmonic generation, emergent Weyl fermions, and other fascinating phenomena. It is expected that if time-reversal symmetry is also broken, additional magneto-electric effects can emerge from the interplay between magnetism and electronic order. Here we report topological conducting properties in the non-centrosymmetric magnet PrAlGe. By photoemission spectroscopy, we observe an arc parametrizing surface-localized states---a topological arc. Using the bulk-boundary correspondence, we conclude that these arcs correspond to projected topological charges of $\pm{1}$ in the surface Brillouin zone, demonstrating the presence of magnetic Weyl quasiparticles in bulk. We further observe a large anomalous Hall response, arising from diverging bulk Berry curvature fields associated with the magnetic Weyl band structure. Our results demonstrate a topological phase with robust electronic surface states and anomalous transport in a non-centrosymmetric magnet for the first time, providing a novel material platform to study the interplay between magnetic order, band topology and transport.

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Daniel S. Sanchez, Guoqing Chang, Ilya Belopolski, Hong Lu, Jia-Xin Yin, Nasser Alidoust, Xitong Xu, Tyler A. Cochran, Xiao Zhang, Yi Bian, Songtian S. Zhang, Yi-Yuan Liu, Jie Ma, Guang Bian, Hsin Lin, Su-Yang Xu, Shuang Jia, M. Zahid Hasan. 2020-06-25. Observation of Weyl fermions in a magnetic non-centrosymmetric crystal. https://doi.org/10.1038/s41467-020-16879-1

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