Dynamic-to-static crossover in the acoustic attenuation of

G. Baldi; P. Benassi; L. E. Bove; S. Caponi; E. Fabiani; D. Fioretto; A. Fontana; A. Giugni; M. Nardone; M. Sampoli; F. Scarponi

doi:10.1209/0295-5075/78/36001

All issues

Volume 78 / No 3 (May 2007)

EPL, 78 3 (2007) 36001

Abstract

Issue		EPL Volume 78, Number 3, May 2007


Article Number		36001
Number of page(s)		6
Section		Condensed Matter: Structural, Mechanical and Thermal Properties
DOI		https://doi.org/10.1209/0295-5075/78/36001
Published online		16 April 2007

EPL, 78 (2007) 36001

Dynamic-to-static crossover in the acoustic attenuation of $\chem{v\tx{-}GeO_2}$

G. Baldi¹^,2, P. Benassi³^,2, L. E. Bove⁴^,2, S. Caponi¹^,2, E. Fabiani⁵, D. Fioretto⁶^,2, A. Fontana¹^,2, A. Giugni³^,2, M. Nardone³^,2, M. Sampoli⁷^,2 and F. Scarponi⁶

¹ Dipartimento di Fisica, Università di Trento - 38050 Povo, Trento, Italy
² Research Center SOFT INFM-CNR, c/o Università di Roma “La Sapienza” - 00185 Roma, Italy
³ Dipartimento di Fisica, Università di L'Aquila - 67010 Coppito, L'Aquila, Italy
⁴ Departement Physique des Milieux Denses CNRS-IMPMC, Universitè Paris 6 - F-75015 Paris, France
⁵ Universitè Joseph Fourier c/o Institut de Biologie Structurale and CRG-IN13 at Institut Laue-Langevin (ILL) - B.P. 156 Grenoble Cedex 9, France
⁶ Dipartimento di Fisica, Università di Perugia - 06123 Perugia, Italy
⁷ Dipartimento di Energetica, Università di Firenze - 50139 Firenze, Italy

Received: 11 September 2006
Accepted: 15 March 2007

Abstract

The acoustic attenuation of vitreous germania (v-GeO₂) has been measured over more than three decades in frequency, by means of neutron scattering at high-frequency (THz), visible light scattering and the newly developed technique of Brillouin ultraviolet scattering at lower frequencies (15 $\hbox{--}$ 50 GHz). The experiments are supported by a molecular dynamics study of a simulated sample of v-GeO₂. The temperature dependence, from 80 K up to the glass transition temperature, shows a persistence of the dynamical nature of the attenuation in the GHz range and a simultaneous increase of the contribution coming from the structural disorder. At higher frequencies clear evidences of a crossover to a region where the attenuation is induced only by the topological disorder are found.

PACS: 63.50.+x – Vibrational states in disordered systems / 78.35.+c – Brillouin and Rayleigh scattering; other light scattering / 61.12.Ex – Neutron scattering (including small-angle scattering)

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