Physics of Phonon-Polaritons in Amorphous Materials
arXiv:2004.12358 · doi:10.1063/5.0033371
Abstract
The nature of bosonic excitations in disordered materials has remained elusive due to the difficulties in defining key concepts such as quasi-particles in the presence of disorder. We report on the experimental observation of phonon-polaritons in glasses, including a boson peak (BP), i.e. excess of THz modes over the Debye law. A theoretical framework based on the concept of diffusons is developed to model the broadening linewidth of the polariton due to disorder-induced scattering. It is shown that the scaling of the BP frequency with the diffusion constant of the linewidth strongly correlates with that of the Ioffe-Regel (IR) crossover frequency of the polariton. This result demonstrates the universality of the BP in the low-energy spectra of collective bosonic-like excitations in glasses, well beyond the traditional case of acoustic phonons, and establishes the IR crossover as the fundamental physical mechanism behind the BP.
arXiv commentv1: 5+4 pages, 4+6 figures
References in corpus (19)
- Glass-specific behavior in the damping of acoustic-like vibrations
- Universal origin of boson peak vibrational anomalies in ordered crystals and in amorphous materials
- Local inversion-symmetry breaking controls the boson peak in glasses and crystals
- Collective Excitations of Quantum Anomalous Hall Ferromagnets in Twisted Bilayer Graphene
- The Ioffe-Regel criterion and diffusion of vibrations in random lattices
- Universal Features of Terahertz Absorption in Disordered Materials
- Acoustic excitations and elastic heterogeneities in disordered solids
- Evidence of anomalous dispersion of the generalized sound velocity in glasses
- Boson peak dynamics of glassy glucose studied by integrated terahertz-band spectroscopy
- Sound attenuation in stable glasses
- Emergence of glassy features in halomethane crystals
- Relaxation and vibrational properties in metal alloys and other disordered systems
- Glassy anomalies in the low-temperature thermal properties of a minimally disordered crystalline solid
- Disentangling boson peaks and Van Hove singularities in a model glass
- Unified theory of vibrational spectra in amorphous materials
- Detection of boson peak and fractal dynamics of disordered system using terahertz spectroscopy
- Vibrational density of states and specific heat in glasses from random matrix theory
- Hydrodynamics of disordered marginally-stable matter
- Analytical prediction of logarithmic Rayleigh scattering in amorphous solids from tensorial heterogeneous elasticity with power-law disorder