Anharmonic damping of terahertz acoustic waves in a network glass and its effect on the density of vibrational states.
We report the observation, by means of high-resolution inelastic x-ray scattering, of an unusually large temperature dependence of the sound attenuation of a network glass at terahertz frequency, an unprecedentedly observed phenomenon. The anharmonicity can be ascribed to the interaction between the propagating acoustic wave and the bath of thermal vibrations. At low temperatures the sound attenuation follows a Rayleigh-Gans scattering law. As the temperature is increased the anharmonic process sets in, resulting in an almost quadratic frequency dependence of the damping in the entire frequency range. We show that the temperature variation of the sound damping accounts quantitatively for the temperature dependence of the density of vibrational states.
IMEM-CNR Institute, Parma Science Park, I-43124 Parma, Italy.
G
G
Baldi
Institut Lumière Matière, UMR 5306 Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne, France and SIMAP, UJF, CNRS, INP Grenoble, F-38402 St. Martin d'Heres, France.
V M
VM
Giordano
European Synchrotron Radiation Facility, BP220, F-38043 Grenoble, France.
B
B
Ruta
Industrial Engineering Department, Trento University, I-38123 Trento, Italy.
R
R
Dal Maschio
Physics Department, Trento University, I-38123 Povo, Trento, Italy and IPCF-CNR, UOS of Roma, c/o Roma University "La Sapienza," I-00185 Roma, Italy.
A
A
Fontana
Physics Department, Trento University, I-38123 Povo, Trento, Italy.
G
G
Monaco