Unifying description of the vibrational anomalies of amorphous materials

Microscopic analysis of sound attenuation in low-temperature amorphous solids reveals quantitative importance of non-affine effects

“…Finally, Mahajan and Pica Ciamarra [21] argued that sound attenuation is proportional to the square of the disorder parameter according to a version of fluctuating elasticity theory that incorporates an elastic correlation length [11,22]. They relied upon a relation between the boson peak, the speed of sound, and an elastic correlation length to show that the speed of sound and the boson peak frequency can be used to infer the change of the sound damping coefficient.…”

A unified quantifier of mechanical disorder in solids

“…Having at hand estimations for χ, we now turn to estimating γ via the sample-to-sample fluctuations ∆µ of the shear modulus µ. Support for the equivalence between these procedures has been presented recently in [27]. To this aim, we first stress that the sample-to-sample distribution p(µ; N ) of glasses of size N shows strong finite-size effects, as discussed at length in [13,19].…”

“…In the context of the attenuation rate of plane waves in disordered media, the ∼ ω d+1 scaling is known as Rayleigh scattering [24], and has been observed in numerical simulations in recent years [19,22,[25][26][27].…”

“…( 8))we employed sample-to-sample statistics instead of spatial coarse-graining procedures. The equivalence of these two approaches to evaluating γ was recently argued for in [27] based on detailed analyses of computer glasses. A deeper understanding of this equivalence and its further reinforcement is left for future investigations.…”

Transport and relaxation of current-generated nonequilibrium phonons from nonlocal electronic measurements

“…Since inelastic scattering requires anharmonicity, but weak anharmonicity responsible for the few-phonon processes cannot account for our observations, we conclude that secondary phonons are likely generated due to strongly anharmonic dynamics. Such dynamics may be related to the bosonic peak ubiquitous in the spectra of amorphous materials [37][38][39] and to the problem of phonon glass [40,41], and may be associated with quasilocalized nonlinear defect states such as bistable atomic configurations [top inset in Fig. 4(a)], as well as interstitial impurities and incoherent interfaces [42,43].…”