Title: Sound attenuation and anharmonic damping in solids with correlated disorder
Author(s):

	W. Schirmacher (Physik-Department E13, Technische Universität München, James-Franck-Strasse 1, D-85747 Garching, Germany; Fachbereich Physik, Universität Mainz, Germany) ,
	C. Tomaras (Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, Theresienstr. 37, D-80333 München, Germany) ,
	B. Schmid (Fachbereich Physik, Universität Mainz, Germany) ,
	G. Baldi (ESRF Grenoble) ,
	G. Viliani (Dipt. di Fisica, Universit\'a di Trento, Italy) ,
	G. Ruocco (Dipt. di Fisica, Universit Ža di Roma, Italy; IPCF-CNR, Sezione di Roma, c/o Sapienza Universita' di Roma, Italy) ,
	T. Scopigno (Dipt. di Fisica, Universit Ža di Roma, Italy; IPCF-CNR, Sezione di Roma, c/o Sapienza Universita' di Roma, Italy)

We study via self-consistent Born approximation a model for sound waves in a disordered environment, in which the local fluctuations of the shear modulus G are spatially correlated with a certain correlation length ξ. The theory predicts an enhancement of the density of states over Debye's ω² law (boson peak) whose intensity increases for increasing correlation length, and whose frequency position is shifted downwards as 1/ξ. Moreover, the predicted disorder-induced sound attenuation coefficient Γ(k) obeys a universal scaling law ξ Γ(k) = f(kξ) for a given variance of G. Finally, the inclusion of the lowest-order contribution to the anharmonic sound damping into the theory allows us to reconcile apparently contradictory recent experimental data in amorphous SiO₂.

Key words: sound attenuation, vibrational properties of disordered solids, boson peak, anharmonic interactions
PACS: 63.50.-x, 43.20.+g, 65.60.+a

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