2019/05/31 by Avraham Moriel, Geert Kapteijns, Corrado Rainone +3 · 1 citation
Earth and Planetary Sciences · Materials Science · Mathematics · Physics and Astronomy · #Attenuation #Condensed matter physics #Geological and Geochemical Analysis #Geometry #Material Dynamics and Properties #Mathematics #Number density #Phonon #Physics #Quantum mechanics #Rayleigh scattering #Scaling #Scattering #Theoretical and Computational Physics #Wavenumber #cond-mat.mtrl-sci #cond-mat.soft
paper · pdf · doi:10.1063/1.5111192
published as The Journal of Chemical Physics 151, 104503 (2019) · 15 pages, 10 figures (including appendices). v2 includes a new appendix with 2 figures (Fig.7 & Fig.8)
arxiv created 2019/08/29 · openalex publication_date 2019/09/13 · openalex created_date 2020/11/23 · arxiv updated 2021/03/23 · openalex updated_date 2026/08/05
The attenuation of long-wavelength phonons (waves) by glassy disorder plays a central role in various glass anomalies, yet it is neither fully characterized nor fully understood. Of particular importance is the scaling of the attenuation rate Γ(k) with small wavenumbers k → 0 in the thermodynamic limit of macroscopic glasses. Here, we use a combination of theory and extensive computer simulations to show that the macroscopic low-frequency behavior emerges at intermediate frequencies in finite-size glasses, above a recently identified crossover wavenumber k†, where phonons are no longer quantized into bands. For k < k†, finite-size effects dominate Γ(k), which is quantitatively described by a theory of disordered phonon bands. For k > k†, we find that Γ(k) is affected by the number of quasilocalized nonphononic excitations, a generic signature of glasses that feature a universal density of states. In particular, we show that in a frequency range in which this number is small, Γ(k) follows a Rayleigh scattering scaling ∼k¯d+1 (¯d is the spatial dimension) and that in a frequency range in which this number is sufficiently large, the recently observed generalized-Rayleigh scaling of the form ∼k¯d+1 log(k0/k) emerges (k0 > k† is a characteristic wavenumber). Our results suggest that macroscopic glasses—and, in particular, glasses generated by conventional laboratory quenches that are known to strongly suppress quasilocalized nonphononic excitations—exhibit Rayleigh scaling at the lowest wavenumbers k and a crossover to generalized-Rayleigh scaling at higher k. Some supporting experimental evidence from recent literature is presented.