Theoretical and Experimental Discovery of Topological Chiral Crystals

Invited

Abstract

We have shown that Kramers-Weyl fermions are a universal topological electronic property of all non-magnetic chiral crystals with spin-orbit coupling and are guaranteed by structural chirality, lattice translation and time-reversal symmetry. We determined that all point-like nodal degeneracies in non-magnetic chiral crystals with relevant spin-orbit coupling carry non-trivial Chern numbers. Kramers–Weyl materials can exhibit a monopole-like electron spin texture and topologically non-trivial bulk Fermi surfaces over an unusually large energy window [G. Chang et al. Nature Materials 17, 978-985 (2018)]. Among all the materials, we predicted the RhSi family to exhibit the ideal topological band structures, displaying the largest possible momentum separation of compensative chiral fermions, the largest proposed topologically nontrivial energy window, and the longest possible Fermi arcs on its surface [G. Chang et al. PRL 119, 206401 (2017)]. We present the theory of exotic nonlinear optical responses of topological chiral crystals, including quantized photogalvanic effect in RhSi and robust photocurrents from Fermi arc surface states [G. Chang et al. PRL 119, 206401 (2017) and arXiv:1906.03207 (2019)]. We also discuss the experimental discovery of RhSi as topological chiral crystals [D. S. Sanchez et al. Nature 567, 500-505 (2019)] and additional experiments that our discovery has enabled. (This work is in collaboration with D. S. Sanchez, I. Belopolski, T. A. Cochran, B. J. Wieder, F. Schindler, J. Yin, S. S. Zhang, S. Huang, B. Singh, T. Chang, A. Bansil, T. Neupert, S.-Y. Xu, H. Lin, and M. Zahid Hasan)

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Presenters

  • Guoqing Chang

    Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton University

Authors

  • Guoqing Chang

    Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton University

  • Daniel S. Sanchez

    Princeton University

  • Ilya Belopolski

    Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton University

  • Tyler Cochran

    Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton University, Physics, Princeton University

  • Benjamin Wieder

    Princeton University

  • Frank Schindler

    University of Zurich, Department of Physics, University of Zurich

  • Jiaxin Yin

    Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton University, Physics, Princeton University

  • Songtian Sonia Zhang

    Princeton University, Physics, Princeton University

  • Shin-Ming Huang

    National Sun Yat-sen University, Natl Sun Yat Sen Univ, Physics, Natl Sun Yat Sen Univ, National Sun Yat-Sen University

  • Bahadur Singh

    Northeastern University, Physics, Northeastern University, SZU-NUS Collaborative Center, ShenZhen University, Department of Physics, Northeastern University

  • Tay-Rong Chang

    National Cheng Kung University, Physics, National Cheng Kung University, Department of Physics, National Cheng Kung University, National Cheng Kung University, Taiwan

  • Arun Bansil

    Northeastern University, Physics, Northeastern University

  • Titus Neupert

    Univ of Zurich, University of Zurich, Department of Physics, University of Zurich, Physics, University of Zurich

  • Suyang Xu

    Massachusetts Institute of Technology, Massachusetts Institute of Technology MIT, Physics, Massachusetts Institute of Technology, Harvard university, Harvard University, Havard University

  • Hsin Lin

    Academia Sinica, Physics, Academia Sinica, Institute of Physics, Academia Sinica, Taipei, Taiwan, Institute of Physics, Academia Sinica

  • Zahid Hasan

    Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton University, Physics, Princeton University