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The time-honored Allen-Feldman theory of heat transport in glasses is generally assumed to predict a finite value for the thermal conductivity, even if it neglects the anharmonic broadening of vibrational normal modes. We demonstrate that…

Disordered Systems and Neural Networks · Physics 2023-07-19 Alfredo Fiorentino , Enrico Drigo , Stefano Baroni , Paolo Pegolo

The boson peak appears in all amorphous solids and is an excess of vibrational states at low frequencies compared to the phonon spectrum of the corresponding crystal. Until recently, the consensus was that it originated from "defects" in…

Materials Science · Physics 2016-12-16 Tobias Brink , Leonie Koch , Karsten Albe

The velocity and absorption coefficient for the plane sound waves in a classical gas are obtained by solving the Boltzmann kinetic equation, which describes the reaction of the single-particle distribution function to a periodic external…

Statistical Mechanics · Physics 2018-01-29 A. G. Magner , M. I. Gorenstein , U. V. Grygoriev

Glasses and other non-crystalline solids exhibit thermal and acoustic properties at low temperatures anomalously different from those found in crystalline solids, and with a remarkable degree of universality. Below a few K, these universal…

Disordered Systems and Neural Networks · Physics 2014-07-25 Tomás Pérez-Castañeda , Cristian Rodríguez-Tinoco , Javier Rodríguez-Viejo , Miguel A. Ramos

We present a systematic theory of the phonon Hall effect in a ballistic crystal lattice system, and apply it on the kagome lattice which is ubiquitous in various real materials. By proposing a proper second quantization for the non-Hermite…

Materials Science · Physics 2011-07-15 Lifa Zhang , Jie Ren , Jian-Sheng Wang , Baowen Li

In this work, we show how states with conserved numbers of dynamical defects (strings, domain walls, etc.) can be understood as possessing generalised global symmetries even when the microscopic origins of these symmetries are unknown.…

High Energy Physics - Theory · Physics 2018-05-18 Sašo Grozdanov , Napat Poovuttikul

Boson peak (BP) dynamics refers to the universal excitation in the terahertz region of glass. In this study, the universal dynamics of BP were quantitatively evaluated in various glassy materials based on the heterogeneous elasticity theory…

We present a general harmonic theory for the temperature dependence of phonon-renormalized properties of solids. Firstly, we formulate a perturbation theory in phonon-phonon interactions to calculate the phonon renormalization of physical…

Materials Science · Physics 2015-10-28 Bartomeu Monserrat , G. J. Conduit , R. J. Needs

The universal bimodal distribution of transmission eigenvalues in lossless diffusive systems un- derpins such celebrated phenomena as universal conductance fluctuations, quantum shot noise in condensed matter physics and enhanced…

Optics · Physics 2016-03-09 A. Yamilov , S. Petrenko , R. Sarma , H. Cao

The vibrational anomalies of glasses, in particular the boson peak, are addressed from the standpoint of heterogeneous elasticity, namely the spatial fluctuations of elastic constants caused by the structural disorder of the amorphous…

Disordered Systems and Neural Networks · Physics 2020-09-15 Walter Schirmacher , Giancarlo Ruocco

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…

Soft Condensed Matter · Physics 2024-06-10 Cunyuan Jiang , Matteo Baggioli , Jack F. Douglas

We conduct experiments on two-dimensional packings of colloidal thermosensitive hydrogel particles whose packing fraction can be tuned above the jamming transition by varying the temperature. By measuring displacement correlations between…

The theory of anomalous Hall effect for the heat transfer in a paramagnetic dielectric, discovered experimentally in [1], is developed. The appearance of the phonon heat flux normal to both the temperature gradient and the magnetic field is…

Other Condensed Matter · Physics 2009-11-13 Yu. Kagan , L. A. Maksimov

The boson peak in metallic glasses is modeled in terms of local structural shear rearrangements. Using Eshelby's solution of the corresponding elasticity theory problem (J. D. Eshelby, Proc. Roy. Soc. A241, 376 (1957)), one can calculate…

Disordered Systems and Neural Networks · Physics 2009-09-24 U. Buchenau , H. R. Schober

Our direct atomic simulations reveal that a thermally activated phonon mode involves a large population of elastic wavepackets. These excitations are characterized by a wide distribution of lifetimes and coherence times expressing particle-…

Mesoscale and Nanoscale Physics · Physics 2021-05-26 Zhongwei Zhang , Yangyu Guo , Marc Bescond , Jie Chen , Masahiro Nomura , Sebastian Volz

Transport of strongly interacting fermions governs modern materials -- from the high-$T_c$ cuprates to bilayer graphene --, but also nuclear fission, the merging of neutron stars and the expansion of the early universe. Here we observe a…

Using a simple thermo-hydrodynamic model that respects relativistic causality, we revisit the analysis of qualitative features of acoustic oscillations in the photon-baryon fluid. The growing photon mean free path introduces transient…

Astrophysics · Physics 2008-11-26 Roy Maartens , Josep Triginer

Theory of superconductivity generated in one atomic layer thick two dimensional electron gas by a single flat band of high energy longitudinal optical phonons is considered. The polar dielectric $SrTiO_{3}$ (STO) exhibits such an energetic…

Superconductivity · Physics 2016-08-03 Baruch Rosenstein , B. Ya. Shapiro , I. Shapiro , Dingping Li

Phonon spectra in solids often display anomalies that defy the simple Debye law, most prominently the van Hove singularity in crystals and the boson peak in glasses. Although traditionally regarded as distinct, both features are…

Materials Science · Physics 2025-10-24 Alessio Zaccone

The optical absorption of a many (continuum) polaron gas is derived in the framework of a variational approach at zero temperature and weak or intermediate electron-phonon coupling strength. We derive a compact formula for the optical…

Strongly Correlated Electrons · Physics 2009-10-31 J. Tempere , J. T. Devreese