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Title: Experimental evidence of hourglass fermion in the candidate nonsymmorphic topological insulator KHgSb

Topological insulators (TIs) host novel states of quantum matter characterized by nontrivial conducting boundary states connecting valence and conduction bulk bands. All TIs discovered experimentally so far rely on either time-reversal or mirror crystal symmorphic symmetry to protect massless Dirac-like boundary states. Several materials were recently proposed to be TIs with nonsymmorphic symmetry, where a glide mirror protects exotic surface fermions with hourglass-shaped dispersion. However, an experimental confirmation of this new fermion is missing. Using angle-resolved photoemission spectroscopy, we provide experimental evidence of hourglass fermions on the (010) surface of crystalline KHgSb, whereas the (001) surface has no boundary state, in agreement with first-principles calculations. Our study will stimulate further research activities of topological properties of nonsymmorphic materials.
Authors:
 [1] ;  [1] ;  [1] ; ORCiD logo [2] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [3] ;  [4] ;  [4] ;  [4] ; ORCiD logo [4] ; ORCiD logo [5] ;  [2] ;  [1] ;  [5] ; ORCiD logo [3]
  1. Chinese Academy of Sciences (CAS), Beijing (China)
  2. Princeton Univ., NJ (United States)
  3. Chinese Academy of Sciences (CAS), Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Univ. of Chinese Academy of Sciences, Beijing (China)
  4. Univ. of Tokyo (Japan)
  5. Chinese Academy of Sciences (CAS), Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
Publication Date:
Grant/Contract Number:
sC0016239
Type:
Accepted Manuscript
Journal Name:
Science Advances
Additional Journal Information:
Journal Volume: 3; Journal Issue: 5; Journal ID: ISSN 2375-2548
Publisher:
AAAS
Research Org:
Princeton Univ., NJ (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1426779