Stringlet Excitation Model of the Boson Peak

Abstract

The boson peak (BP), a low-energy excess in the vibrational density of states over the Debye contribution, is often identified as a characteristic of amorphous solid materials. Despite decades of efforts, its microscopic origin still remains a mystery. Recently, it has been proposed, and corroborated with simulations, that the BP might stem from intrinsic localized modes involving one-dimensional (1D) string-like excitations (``stringlets"). We build on a theory originally proposed by Lund that describes the localized modes as 1D vibrating strings, but we specify the stringlet size distribution to be exponential, as observed in simulations. We provide an analytical prediction for the BP frequency ${\omega }_{BP}$ in the temperature regime well below the observed glass transition temperature $T_g$. The prediction involves no free parameters and accords quantitatively with prior simulation observations in 2D and 3D model glasses based on inverse power law potentials. The comparison of the string model to observations is more uncertain when compared to simulations of an Al-Sm metallic glass material at temperatures well above $T_g$. Nonetheless, our stringlet model of the BP naturally reproduces the softening of the BP frequency upon heating and offers an analytical explanation for the experimentally observed scaling with the shear modulus in the glass state and changes in this scaling in simulations of glass-forming liquids. Finally, the theoretical analysis highlights the existence of a strong damping for the stringlet modes above $T_g$, which leads to a large low-frequency contribution to the 3D vibrational density of states, observed in both experiments and simulations.

arXiv commentv3: matching the published version. arXiv admin note: substantial text overlap with arXiv:2307.12839

References in corpus (42)

• String-like Clusters and Cooperative Motion in a Model Glass-Forming Liquid
• Phonon-glass electron-crystal thermoelectric clathrates: Experiments and theory
• Anharmonicity, vibrational instability and Boson peak in glasses
• Continuum limit of the vibrational properties of amorphous solids
• Statistics and properties of low-frequency vibrational modes in structural glasses
• Inhomogeneous elastic response of silica glass
• The evolution of vibrational excitations in glassy systems
• Glass-specific behavior in the damping of acoustic-like vibrations
• Vibrational instability, two-level systems and Boson peak in glasses
• Universal origin of boson peak vibrational anomalies in ordered crystals and in amorphous materials
• The Ioffe-Regel criterion and diffusion of vibrations in random lattices
• Plasticity in amorphous solids is mediated by topological defects in the displacement field
• q-Breathers in Fermi-Pasta-Ulam chains: existence, localization and stability
• Universal law for the vibrational density of states of liquids
• Fast Dynamics in a Model Metallic Glass-forming Material
• Onsager Loop-Transition and First Order Flux-Line Lattice Melting in High-$T_c$ Superconductors
• Topology of vibrational modes predict plastic events in glasses
• Vibrations and Relaxations in a Soft Sphere Glass: Boson Peak and Structure Factors
• Scaling the Temperature-dependent Boson Peak of Vitreous Silica with the high-frequency Bulk Modulus derived from Brillouin Scattering Data
• Superionic UO2: A Model Anharmonic Crystalline Material
• Emergence of glassy features in halomethane crystals
• Deformations, relaxation and broken symmetries in liquids, solids and glasses: a unified topological field theory
• The Thermodynamics of Cosmic String densities in U(1) Scalar Field Theory
• Boson-peak vibrational modes in glasses feature hybridized phononic and quasilocalized excitations
• Experimental Confirmation of the Universal Law for the Vibrational Density of States of Liquids
• Universal Sound Absorption in Amorphous Solids: A Theory of Elastically Coupled Generic Blocks
• Boson peak, elasticity, and glass transition temperature in polymer glasses: Effects of the rigidity of chain bending
• Slow Relaxation and Phase Space Properties of a Conservative System with Many Degrees of Freedom
• An explanation for the glass-like anomaly in the low-temperature specific heat of incommensurate phases
• The length distribution of vortex strings in U(1) equilibrium scalar field theory
• Correlation between vibrational anomalies and emergent anharmonicity of local potential energy landscape in metallic glasses
• Mean-field model of interacting quasilocalized excitations in glasses
• Hydrodynamics of disordered marginally-stable matter
• The boson peak in the vibrational spectra of glasses
• Low-energy optical phonons induce glassy-like vibrational and thermal anomalies in ordered crystals
• Are universal "anomalous" properties of glasses at low temperatures truly universal?
• Topological defects reveal the plasticity of glasses
• Elastic anomalies in glasses: the string theory understanding in the case of Glycerol and Silica
• A new paradigm for the low-T glassy-like thermal properties of solids
• On the temperature dependence of the density of states of liquids at low energies
• Normal modes, and acoustic properties, of an elastic solid with line defects
• Glassy heat capacity from overdamped phasons and a hypothetical phason-induced superconductivity in incommensurate structures

Cited by in corpus (5)

• Dispersionless Flat Mode and Vibrational Anomaly in Active Brownian Vibrators Induced by String-like Dynamical Defects
• Revealing the Geometrical and Vibrational Properties of the Defects Driving the Boson Peak
• Impact of elastic inhomogeneity on collective dynamical properties investigated by field theoretical description in real space
• The anomalous density of states and quasi-localized vibration through homogeneous thermalization of an inhomogeneous elastic system
• Resonant Coupling and the Non-Phononic Flat Band in Amorphous Solids