Terahertz Phonons in Highly Disordered Crystals

  • U. Happek
  • W. W. Fischer
  • J. A. Campbell
Conference paper
Part of the Springer Series in Solid-State Sciences book series (SSSOL, volume 112)

Abstract

The relaxation of non-equilibrium THz phonons in the mixed-crystal systems Cal−xSrxF2 and Cal−2LaxF2+x has been studied at low temperature. In the Ca1−zSrxF2 system we find only a moderate (up to a factor of two) increase of the relaxation rate, even at high Sr concentrations, and a v5 frequency dependence of the relaxation rate, as is characteristic for spontaneous phonon decay due to lattice anharmonicity, similar to that found in pure CaF2 and SrF2. In Cal−xLaxF2+x however, La concentrations in the order of even 1% reduce the lifetime by up to two orders of magnitude. Furthermore, the relaxation rate increases with the cube of the frequency, indicating the existence of a new mechanism dominating the relaxation of the phonons.

Keywords

Helium 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1993

Authors and Affiliations

  • U. Happek
    • 1
    • 2
  • W. W. Fischer
    • 2
  • J. A. Campbell
    • 3
  1. 1.Laboratory of Atomic and Solid State PhysicsCornell UniversityIthacaUSA
  2. 2.Institut für Angewandte PhysikUniversität RegensburgRegensburgFed. Rep. of Germany
  3. 3.Department of PhysicsUniversity of CanterburyChristchurchNew Zealand

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