Boson peak in glasses

theory

2008 Universal link between the boson peak and transverse phonons in glass

We discovered evidence suggestive of the equality of the boson
peak frequency to the Ioffe–Regel limit for ‘transverse’ phonons, above which transverse phonons no longer propagate. Our results
indicate a possibility that the origin of the boson peak is transverse vibrational modes associated with defective soft structures in
the disordered state. Furthermore, we suggest a possible link between slow structural relaxation and fast boson peak dynamics in
glass-forming systems.

Turlakov 2003 Universal sound absorption in low-temperature glasses

Phenomenologically assuming a sharp decrease of shear relaxation time for large wavevector k > kξ
density modes (where kξ is of order of inverse of several interatomic distances a), I develop a general
elasto-hydrodynamic theory describing the low-energy excitations of glassy and amorphous solids

Heterogeneous Elasticity: The tale of the boson peak Walter Schirmacher, Giancarlo Ruocco

Heterogeneous shear elasticity of glasses: the origin of the boson peak

... in the boson peak region are produced by spatial fluctuations of dilatation-free shear stresses

van Hove

2011 Equivalence of the Boson Peak in Glasses to the Transverse Acoustic van Hove Singularity in Crystals
A. I. Chumakov

2011 Reiner Zorn Experiments suggest that the celebrated “boson peak”—a low-frequency vibrational feature characteristic of amorphous materials—may be related to a well-known phonon singularity in ordered crystalline materials.

2017 Universal structural softening in metallic glasses indicated by boson heat capacity peak M. Q. Jiang,

A main finding of the present study is that the boson heat capacity peaks involving both phonic and electronic contributions show an inversely linear correlation between their heights and position temperatures

... can be understood in terms of transverse soft modes associated with local soft regions

We further suggest a possibility that the linear evolution of the fast boson peaks can probe into the slow structural softening across the glass transition, and the two dynamic processes are controlled by the short-time shear modulus associated with local soft regions in fragile glasses

Baggioli 2019 Vibrational density of states and specific heat in glasses from random matrix theory

The model is also able to reproduce, for the first time, the experimentally observed inverse proportionality between the boson peak in the specific heat and the shear modulus

The linear in T regime is controlled by the low-frequency side of the random matrix spectrum, which goes as D(ω) = Aω + B, stemming
directly from the Marchenko-Pastur scaling in the low eigenvalue regime,

This result shows that at very low T the specific heat of the random spring network is linear in T, and that this
behaviour is controlled by random matrix statistics and its interplay with the Goldstone phonons.

linear-T specific heat

2019 From random matrix theory to linear-in-T specific heat in glasses Matteo Baggioli, Rico Milkus, Alessio Zaccone

The model is also able to reproduce, for the first time, the experimentally
observed inverse proportionality between the boson peak in the specific heat and the shear modulus

2020 A new paradigm for the low-T glassy-like thermal properties of solids

New experimental and theoretical observations have questioned the origin of the boson peak and the linear in T specific heat exclusively from disorder and TLS.

Using the formal analogy between phason modes (e.g. in quasicrystals and incommensurate lattices) and
diffusons, and between amplitude modes and optical phonons, we suggest the existence of a more
universal physics behind these properties.