Universal Form of the Low-Energy (2 to 10 meV) Vibrational Spectrum of Glasses

Abstract

By means of inelastic cold neutron scattering the density of vibrational states (DVS) has been determined for a series of vitreous materials: SiO2, As2S3 and metallic glass Mg70Zn30. In the low-energy range of the spectrum (E ∼ (2 ÷ 10) meV) for these materials DVS reveals a universal, but non-Debye form. The data obtained are compared to different models. A comparison with the Raman scattering data provides the spectral dependence for the coupling of the light to the vibrational excitations.