Unified theory of vibrational spectra in amorphous materials

Abstract

The phonon spectra of solids, described through the measurable vibrational density of states (VDOS), provide a wealth of information about the underlying atomic structure and bonding, and they determine fundamental macroscopic properties such as specific heat, thermal conductivity and superconductivity. In amorphous solids, structural disorder generates a number of poorly understood phenomena that are absent in crystals. Starting from an effective field theory description which accounts for disorder in terms of momentum diffusion, we provide a unified theoretical description of the VDOS of amorphous materials. The theory provides an excellent description of the simulated/experimental VDOS of two quite different materials (silica glass and amorphous Si) with very few non-trivial fitting parameters. In particular, the phonons speeds and diffusive linewidths obtained from the fits are fully consistent with the tabulated values from experiments. This semi-analytical approach solves the long-standing problem of describing and explaining the features of the VDOS and Raman spectra of amorphous solids in relation with the underlying acoustic dispersion relations and acoustic attenuation. Furthermore, it can be used in a reverse-engineered way to estimate phonon dispersion relations, acoustic attenuation and dynamic structure factors from a simple fitting of the VDOS with the presented model.

arXiv comment5 pages, 4 figures

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Cited by in corpus (15)

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• Anharmonic phonon damping enhances the $T_c$ of BCS-type superconductors
• Effective Theory of Superconductivity in Strongly-Coupled Amorphous Materials
• Field Theory of Dissipative Systems with Gapped Momentum States
• Theory of sound attenuation in amorphous solids from nonaffine motions
• Possible enhancement of the superconducting $T_c$ due to sharp Kohn-like soft phonon anomalies
• Universal non-Debye low-frequency vibrations in sheared amorphous solids
• Black Rubber and the Non-linear Elastic Response of Scale Invariant Solids
• A new paradigm for the low-T glassy-like thermal properties of solids
• Physics of Phonon-Polaritons in Amorphous Materials
• Microstructure and the Boson-peak in thermally-treated In_{x}O films
• Vibrational density of states of amorphous solids with long-ranged power-law correlated disorder in elasticity
• Phonon-confinement theory of thermal conductivity in ultrathin silicon films
• A unified picture of phonon anomalies in crystals and glasses
• Intrinsically ultralow thermal conductivity in all-inorganic superatomic bulk crystals