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Title: Plasmon-enhanced electron-phonon coupling in Dirac surface states of the thin-film topological insulator Bi{sub 2}Se{sub 3}

Raman measurements of a Fano-type surface phonon mode associated with Dirac surface states (SS) in Bi{sub 2}Se{sub 3} topological insulator thin films allowed an unambiguous determination of the electron-phonon coupling strength in Dirac SS as a function of film thickness ranging from 2 to 40 nm. A non-monotonic enhancement of the electron-phonon coupling strength with maximum for the 8–10 nm thick films was observed. The non-monotonicity is suggested to originate from plasmon-phonon coupling which enhances electron-phonon coupling when free carrier density in Dirac SS increases with decreasing film thickness and becomes suppressed for thinnest films when anharmonic coupling between in-plane and out-of-plane phonon modes occurs. The observed about four-fold enhancement of electron-phonon coupling in Dirac SS of the 8–10 nm thick Bi{sub 2}Se{sub 3} films with respect to the bulk samples may provide new insights into the origin of superconductivity in this-type materials and their applications.
Authors:
 [1] ;  [2] ; ;  [1]
  1. Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)
  2. (Ukraine)
Publication Date:
OSTI Identifier:
22492797
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 13; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BISMUTH SELENIDES; CARRIER DENSITY; ELECTRON-PHONON COUPLING; PHONONS; SUPERCONDUCTIVITY; SURFACES; THICKNESS; THIN FILMS; TOPOLOGY