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Title: Nonlinear electron dynamics of gold ultrathin films induced by intense terahertz waves

Linear and nonlinear electron dynamics of polycrystalline gold (Au) ultrathin films with thicknesses ranging from 1.4 to 5.8 nm were investigated via transmittance terahertz (THz) spectroscopy with intense electric field transients. We prepared ultrathin films with low surface roughness formed on a Si–(7 × 7) reconstructed surface, leading to the observation of monotonic decrease in THz transmittance with respect to film thickness. Furthermore, at all tested thicknesses, the transmittance decreased nonlinearly by 10%–30% with the application if high-intensity THz electric fields. Based on a Drude-model analysis, we found a significant decrease in the damping constant induced by the THz electric field, indicating that electrons are driven beyond the polycrystalline grain boundaries in Au thin films, and consequently leading to the suppression of the electron–boundary scattering rate.
Authors:
; ;  [1] ; ;  [2] ;  [3] ;  [1] ;  [3] ;  [3] ;  [3] ;  [3]
  1. Department of Physics, Graduate School of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)
  2. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044 (Japan)
  3. (Japan)
Publication Date:
OSTI Identifier:
22395517
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION SPECTROSCOPY; DAMPING; ELECTRIC FIELDS; ELECTRONS; GOLD; GRAIN BOUNDARIES; NONLINEAR PROBLEMS; POLYCRYSTALS; ROUGHNESS; SURFACES; THIN FILMS; TRANSIENTS