Disordered crystals reveal soft quasilocalized glassy excitations

Abstract

Structural glasses formed by quenching a melt are known to host a population of low-energy quasilocalized (nonphononic) excitations whose frequencies $\omega$ follow a universal $\sim {\omega }^4$ distribution as $\omega \to 0$, independently of the glass formation history, the interparticle interaction potential or spatial dimension. Here, we show that the universal quartic law of nonphononic excitations also holds in disordered crystals featuring finite long-range order, which is absent in their glassy counterparts. We thus establish that the degree of universality of the quartic law extends beyond structural glasses quenched from a melt. We further find that disordered crystals, whose level of disorder can be continuously controlled, host many more quasilocalized excitations than expected based on their degree of mechanical disorder -- quantified by the relative fluctuations of the shear modulus -- as compared to structural glasses featuring a similar degree of mechanical disorder. Finally, we show that the stability bound on nonlinear quasilocalized excitations -- previously established in structural glasses -- also holds in disordered crystals. Our results are related to glass-like anomalies experimentally observed in disordered crystals. More broadly, they constitute an important step towards tracing the essential ingredients necessary for the emergence of universal nonphononic excitations in disordered solids.

9 pages, 5 figures, including appendics

References in corpus (16)

• Irreversible reorganization in a supercooled liquid originates from localised soft modes
• Low-energy quasilocalized excitations in structural glasses
• Acoustic excitations and elastic heterogeneities in disordered solids
• Nonlinear modes disentangle glassy and Goldstone modes in structural glasses
• Emergence of glassy features in halomethane crystals
• Low-frequency vibrational spectrum of mean-field disordered systems
• Elastic moduli fluctuations predict wave attenuation rates in glasses
• Glassy anomalies in the low-temperature thermal properties of a minimally disordered crystalline solid
• Mechanical disorder of sticky-sphere glasses. I. Effect of attractive interactions
• Unifying description of the vibrational anomalies of amorphous materials
• Robustness of Density of Low Frequency States in Amorphous Solids
• Marginal stability of soft anharmonic mean field spin glasses
• Mean-field model of interacting quasilocalized excitations in glasses
• A unified quantifier of mechanical disorder in solids
• Delocalization transition in low energy excitation modes of vector spin glasses
• Internally-stressed and positionally-disordered minimal complexes yield glasslike nonphononic excitations

Cited by in corpus (10)

• Boson-peak vibrational modes in glasses feature hybridized phononic and quasilocalized excitations
• The boson peak in the vibrational spectra of glasses
• Atomic dynamics in fluids: Normal mode analysis revisited
• Variability of mesoscopic mechanical disorder in disordered solids
• Specific heat at low temperatures in quasiplanar molecular crystals: Where do glassy anomalies in minimally disordered crystals come from?
• Testing the Heterogeneous-Elasticity Theory for low-energy excitations in structural glasses
• Revealing the Geometrical and Vibrational Properties of the Defects Driving the Boson Peak
• Enumerating low-frequency nonphononic vibrations in computer glasses
• Universal Jamming Criticality and Self-Organizing Principles from Disorder to the Limit of Perfect Crystalline Order
• Anomalous enhancement of thermal radiation transport by quasidisorder