Related papers: Physics of Phonon-Polaritons in Amorphous Material…
The boson peak is a characteristic anomaly of amorphous solids broadly defined as a low-energy excess in the density of states and heat capacity compared to the textbook predictions of Debye theory. The origin of this anomaly has long been…
The translational symmetry of solids gives rise to the existence of low-frequency phonons. In ordered systems, some phonons characterized by different wavevectors are degenerate, i.e. they share the same frequency $\omega$; in finite-size…
Polaritons are hybrid light-matter quasi-particles that have gathered a significant attention for their capability to show room temperature and out-of-equilibrium Bose-Einstein condensation. More recently, a novel class of ultrafast optical…
Exciton-polaritons are light-matter hybrid quasi-particles that have emerged as a flexible platform for developing quantum technologies and engineering material properties. However, the fundamental mechanistic principles that govern their…
We consider long-wave phonon-polaritons and longitudinal optical phonons in alkali-halide ionic crystals. The model of point charges that are polarized in the self-consistent electromagnetic field in a dielectric environment is used. The…
Polaritons are quasiparticles arising from the strong coupling of electromagnetic waves in cavities and dipolar oscillations in a material medium. In this framework, localized surface plasmon in metallic nanoparticles defining optical…
Low-frequency vibrations of glassy and crystalline orthoterphenyl are studied by means of neutron scattering. Phonon dispersions are measured along the main axes of a single crystal, and the corresponding longitudinal and transversal sound…
By introducing four fundamental types of disorders into a two-dimensional triangular lattice separately, we determine the role of each type of disorder in the vibration of the resulting mass-spring networks. We are concerned mainly with the…
The recently suggested concept of a polaritonic Fourier crystal (PFC) is based on a harmonically-corrugated mirror substrate for a thin pristine polaritonic crystal layer. The propagating polaritons in PFC experience a harmonic and…
We perform molecular-dynamics simulations of the vibrational and the elasto-plastic properties of polymeric glasses and crystals and corresponding atomic systems. We evidence that the elastic scaling of the density of states in the…
We show that the density of states of random wave equations, normalized by the square of the frequency, has a peak - sometimes narrow and sometimes broad - in the range of wave vectors between the disorder correlation length and the…
Black Phosphorus (BP) is unique among layered materials owing to its homonuclear lattice and strong structural anisotropy. While recent investigations on few layers BP have extensively explored the in-plane (a,c) anisotropy, much less…
Exciton-polaritons (EPs) are part-light part-matter quasiparticles that combine large exciton-mediated nonlinearities with long-range coherence, ideal for energy harvesting and nonlinear optics. Optimizing EPs for these applications is…
Hybrid lattice-light modes, known as phonon-polaritons, represent the backbone of advanced protocols based on THz pumping of infrared modes. Here we provide a theoretical framework able to capture the different roles played by…
Atomic vibrations in perfect, slightly defective or mixed crystals are to a large extent well understood since many decades. Theoretical descriptions are thus in excellent agreement with the experiments. As a consequence, phonon-related…
The plasmon and phonon polaritons of two-dimensional (2d) and van-der-Waals materials have recently gained substantial interest. Unfortunately, they are notoriously hard to observe in linear response because of their strong confinement, low…
One of the long-standing issues concerning the thermal properties of amorphous solids is the complex pattern of phonon transport. Recent advances in experiments and computer simulations have indicated a crossover from Rayleigh scattering to…
We performed terahertz time-domain spectroscopy, low-frequency Raman scattering, and Brillouin light scattering on vitreous glucose to investigate the boson peak (BP) dynamics. In the spectra of {\alpha}({\nu})/{\nu}2 [{\alpha}({\nu}) is…
The low-temperature thermal properties of dielectric crystals are governed by acoustic excitations with large wavelengths that are well described by plane waves. This is the Debye model, which rests on the assumption that the medium is an…
The collective excitations of solids are classified as longitudinal and transverse depending on their relative polarization and propagation direction. This seemingly formal classification results in surprisingly distinct types of…