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Title: Unconventional transformation of spin Dirac phase across a topological quantum phase transition

The topology of a topological material can be encoded in its surface states. These surface states can only be removed by a bulk topological quantum phase transition into a trivial phase. Here we use photoemission spectroscopy to image the formation of protected surface states in a topological insulator as we chemically tune the system through a topological transition. Surprisingly, we discover an exotic spin-momentum locked, gapped surface state in the trivial phase that shares many important properties with the actual topological surface state in anticipation of the change of topology. Using a spin-resolved measurement, we show that apart from a surface bandgap these states develop spin textures similar to the topological surface states well before the transition. Our results provide a general paradigm for understanding how surface states in topological phases arise from a quantum phase transition and are suggestive for the future realization of Weyl arcs, condensed matter supersymmetry and other fascinating phenomena in the vicinity of a quantum criticality.
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [1] ;  [5] ;  [6] ;  [7] ;  [1] ;  [8] ;  [5] ;  [1]
  1. Princeton Univ., Princeton, NJ (United States)
  2. Princeton Univ., Princeton, NJ (United States); Peking Univ., Beijing (China)
  3. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
  4. Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ecole Polytechnique Fedeerale de Lausanne, Lausanne (Switzerland)
  5. Northeastern Univ., Boston, MA (United States)
  6. National Tsing Hua Univ., Hsinchu (Taiwan)
  7. National Tsing Hua Univ., Hsinchu (Taiwan); Academia Sinica, Taipei (Taiwan)
  8. National Univ. of Singapore (Singapore)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
FG02-07ER46352; AC03-76SF00098; AC03-76SF00515; FG02-05ER46200
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS physical sciences; applied physics; condensed matter