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Title: Observation of ultrahigh mobility surface states in a topological crystalline insulator by infrared spectroscopy

Topological crystalline insulators possess metallic surface states protected by crystalline symmetry, which are a versatile platform for exploring topological phenomena and potential applications. However, progress in this field has been hindered by the challenge to probe optical and transport properties of the surface states owing to the presence of bulk carriers. Here, we report infrared reflectance measurements of a topological crystalline insulator, (001)-oriented Pb 1-xSn xSe in zero and high magnetic fields. We demonstrate that the far-infrared conductivity is unexpectedly dominated by the surface states as a result of their unique band structure and the consequent small infrared penetration depth. Moreover, our experiments yield a surface mobility of 40,000 cm 2 V -1 s -1, which is one of the highest reported values in topological materials, suggesting the viability of surface-dominated conduction in thin topological crystalline insulator crystals. These findings pave the way for exploring many exotic transport and optical phenomena and applications predicted for topological crystalline insulators.
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [2]
  1. National High Magnetic Field Laboratory, Tallahassee, FL (United States)
  2. Sichuan Univ., Chengdu (China). College of Physical Science and Technolog
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Department of Physics; Hong Kong University of Science and Technology (China). Department of Physics
  4. National Taiwan University, Taipei (Taiwan). Center for Condensed Matter Sciences; Institute of Physics, Academia Sinica, Taipei (Taiwan)
  5. Peking Univ., Beijing (China). International Center for Quantum Materials, School of Physics
  6. National Taiwan University, Taipei (Taiwan). Center for Condensed Matter Sciences
  7. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Department of Physics
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
Country of Publication:
United States
36 MATERIALS SCIENCE; Electronic properties and materials; Surfaces, interfaces and thin films; Topological insulators
OSTI Identifier: