相关论文: Soft Phonon Anomalies in Relaxor Ferroelectrics
Phonon-polaritons (PP) are phonon-photon coupled modes. Using near-forward Raman scattering, the PP of the cubic Zn(1-x)MgxTe (x<0.09) semiconductor alloy could be measured. While the PP-coupling hardly develops in pure ZnTe, minor…
The role of the polarization degree of freedom in lattice dynamics in solids has been underlined recently. We theoretically discover a relaxation mechanism for both linear and circular polarizations of acoustic phonons. In the absence of…
Previous experimental studies of the thermal conductivity of plastically deformed lead crystals in the superconducting state have shown strong anomalies in the thermal conductivity. Similar effects were also found for the thermal…
We report on the exciton formation and relaxation dynamics following photocarrier injection in a single-layer two-dimensional lead-iodide perovskite. We probe the time evolution of four distinct exciton resonances by means of time-resolved…
Phonon spectra of solid substitutional solutions with finite concentrations of impurities were analyzed on the microscopic level. The local phonon densities of impurity atoms were calculated, in particular the formation of quasilocal…
We investigated CdTe nanocrystal tetrapods of different sizes by resonant inelastic light scattering at room temperature and under cryogenic conditions. We observe a strongly resonant behavior of the phonon scattering with the excitonic…
Phonon polaritons (PhPs), the collective phonon oscillations with hybridized electromagnetic fields, concentrate optical fields in the mid-infrared frequency range that matches the vibrational modes of molecules. The utilization of PhPs…
We analyze the ground states and the elementary collective excitations (phonons) of a class of systems, which form cluster crystals in the absence of attractions. Whereas the regime of moderate-to-high-temperatures in the phase diagram has…
The phonon dispersion was measured at room temperature along (0,0,L) in the tetragonal phase of LaFeAsO using inelastic x-ray scattering. Spin-polarized first-principles calculations imposing various types of antiferromagnetic order are in…
Local positional disorder in soft, anharmonic materials has emerged as a central factor in shaping their electronic, vibrational, optical, and transport properties. Viewed mainly as a source of performance degradation, recent theoretical…
We study the polariton relaxation dynamics for different scattering mechanisms as: Phonon and electron scattering procesess. The relaxation polariton is obtained at very short times by solving the Boltzman equation. Instead of the…
It has been known for decades that a magnetic field can deflect phonons as they flow in response to a thermal gradient, producing a thermal Hall effect. Several recent experiments have revealed ratios of the phonon Hall conductivity to the…
Short-range polar orders in the relaxor ferroelectric material PbMg$_{1/3}$Nb$_{2/3}$O$_3$-$28\%$PbTiO$_3$ (PMN-28PT) have been studied using neutron diffuse scattering. An external electric field along [110] direction can affect the…
Synchrotron x-ray scattering studies of anti-ferroelectric nanoregions (AFR) as fluctuations, which give rise to 1/2(hk0) superlattice reflections (alpha spots), were systematically performed in Pb(Mg1/3Nb2/3)O3 (PMN) ferroelectric relaxor.…
We observed that close to a Mott transition, over a small temperature range, the predominance of slow relaxations leads to decoupling of electrons from the thermal bath. This has been established by observation of large deviation of the…
Inelastic neutron scattering measurements are utilized to explore relative changes in the generalized phonon density of states of nanocrystalline Si1xGex thermoelectric materials prepared via ball milling and hot-pressing techniques.…
We consider simple-pole descriptions of soft elastic scattering for pp, pbar p, pi+ p, pi- p, K+ p and K- p. We work at t and s small enough for rescatterings to be neglected, and allow for the presence of a hard pomeron. After building and…
Atomic undercoordination, charge injection, mechanical and thermal activation mediate the properties of a material intrinsically by bond relaxation from one equilibrium to another while the phonon spectrometrics probes the ever-unexpected…
Phonon anomalies observed in various high $T_c$ cuprates by neutron experiments are analyzed theoretically in terms of the stripe concept. The phonon self-energy correction is evaluated by taking into account the charge collective modes of…
The breakdown of translational symmetry at heterointerfaces leads to the emergence of new phonon modes localized near the interface. These interface phonons play an essential role in thermal/electrical transport properties in devices…