# Topological chiral crystals with helicoid-arc quantum states

Daniel S. Sanchez, Ilya Belopolski, Tyler A. Cochran, Xitong Xu, Jia Xin Yin, Guoqing Chang, Weiwei Xie, Kaustuv Manna, Vicky Süß, Cheng Yi Huang, Nasser Alidoust, Daniel Multer, Songtian S. Zhang, Nana Shumiya, Xirui Wang, Guang Qiang Wang, Tay Rong Chang, Claudia Felser, Su Yang Xu, Shuang JiaHsin Lin, M. Zahid Hasan

22 引文 斯高帕斯（Scopus）

### 摘要

The quantum behaviour of electrons in materials is the foundation of modern electronics and information technology 1–11 , and quantum materials with topological electronic and optical properties are essential for realizing quantized electronic responses that can be used for next generation technology. Here we report the first observation of topological quantum properties of chiral crystals 6,7 in the RhSi family. We find that this material class hosts a quantum phase of matter that exhibits nearly ideal topological surface properties originating from the crystals’ structural chirality. Electrons on the surface of these crystals show a highly unusual helicoid fermionic structure that spirals around two high-symmetry momenta, indicating electronic topological chirality. The existence of bulk multiply degenerate band fermions is guaranteed by the crystal symmetries; however, to determine the topological invariant or charge in these chiral crystals, it is essential to identify and study the helicoid topology of the arc states. The helicoid arcs that we observe on the surface characterize the topological charges of ±2, which arise from bulk higher-spin chiral fermions. These topological conductors exhibit giant Fermi arcs of maximum length (π), which are orders of magnitude larger than those found in known chiral Weyl fermion semimetals 5,8–11 . Our results demonstrate an electronic topological state of matter on structurally chiral crystals featuring helicoid-arc quantum states. Such exotic multifold chiral fermion semimetal states could be used to detect a quantized photogalvanic optical response, the chiral magnetic effect and other optoelectronic phenomena predicted for this class of materials 6 .

原文 English 500-505 6 Nature 567 7749 https://doi.org/10.1038/s41586-019-1037-2 Published - 2019 三月 28

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### 引用此

Sanchez, D. S., Belopolski, I., Cochran, T. A., Xu, X., Yin, J. X., Chang, G., Xie, W., Manna, K., Süß, V., Huang, C. Y., Alidoust, N., Multer, D., Zhang, S. S., Shumiya, N., Wang, X., Wang, G. Q., Chang, T. R., Felser, C., Xu, S. Y., ... Hasan, M. Z. (2019). Topological chiral crystals with helicoid-arc quantum states. Nature, 567(7749), 500-505. https://doi.org/10.1038/s41586-019-1037-2