Discovery of a weak topological insulating state and van Hove singularity in triclinic RhBi2

Kyungchan Lee; Gunnar F Lange; Lin-Lin Wang; Brinda Kuthanazhi; Thaís V Trevisan; Na Hyun Jo; Benjamin Schrunk; Peter P Orth; Robert-Jan Slager; Paul C Canfield; Adam Kaminski

doi:10.1038/s41467-021-22136-w

Discovery of a weak topological insulating state and van Hove singularity in triclinic RhBi₂

Nat Commun. 2021 Mar 25;12(1):1855. doi: 10.1038/s41467-021-22136-w.

Authors

Kyungchan Lee^{1

2}, Gunnar F Lange³, Lin-Lin Wang^{1

2}, Brinda Kuthanazhi^{1

2}, Thaís V Trevisan^{1

2}, Na Hyun Jo^{1

2}, Benjamin Schrunk^{1

2}, Peter P Orth^{1

2}, Robert-Jan Slager^{4

5}, Paul C Canfield^{6

7}, Adam Kaminski^{8

9}

Affiliations

¹ Ames Laboratory, Ames, IA, USA.
² Department of Physics and Astronomy, Iowa State University, Ames, IA, USA.
³ TCM Group, Cavendish Laboratory, University of Cambridge, Cambridge, UK.
⁴ TCM Group, Cavendish Laboratory, University of Cambridge, Cambridge, UK. rjs269@cam.ac.uk.
⁵ Department of Physics, Harvard University, Cambridge, MA, USA. rjs269@cam.ac.uk.
⁶ Ames Laboratory, Ames, IA, USA. canfield@ameslab.gov.
⁷ Department of Physics and Astronomy, Iowa State University, Ames, IA, USA. canfield@ameslab.gov.
⁸ Ames Laboratory, Ames, IA, USA. adamkam@ameslab.gov.
⁹ Department of Physics and Astronomy, Iowa State University, Ames, IA, USA. adamkam@ameslab.gov.

Abstract

Time reversal symmetric (TRS) invariant topological insulators (TIs) fullfil a paradigmatic role in the field of topological materials, standing at the origin of its development. Apart from TRS protected strong TIs, it was realized early on that more confounding weak topological insulators (WTI) exist. WTIs depend on translational symmetry and exhibit topological surface states only in certain directions making it significantly more difficult to match the experimental success of strong TIs. We here report on the discovery of a WTI state in RhBi₂ that belongs to the optimal space group P[Formula: see text], which is the only space group where symmetry indicated eigenvalues enumerate all possible invariants due to absence of additional constraining crystalline symmetries. Our ARPES, DFT calculations, and effective model reveal topological surface states with saddle points that are located in the vicinity of a Dirac point resulting in a van Hove singularity (VHS) along the (100) direction close to the Fermi energy (E_F). Due to the combination of exotic features, this material offers great potential as a material platform for novel quantum effects.

Abstract

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