Optical absorption and single–particle excitations in the 2D Holstein t–J model Abstract To discuss the interplay of electronic and lattice degrees of freedom in systems with strong Coulomb correlations we have performed an extensive numerical study of the two–dimensional Holstein t–J model. The model describes the interaction of holes, doped in a quantum antiferromagnet, with a dispersionsless...

We present a detailed investigation of the effects that optical-phonon confinement has on the electronic transport properties of GaAs-based midinfrared multiple-quantum-well MQW quantum cascade lasers QCLs . The macroscopic dielectric continuum model is used to describe the interface IF and confined CF optical phonon modes. Dispersions of the IF modes are obtained by using the transfer matrix m...

This paper discusses the concept of enhancing semiconductor laser performance through tailoring of scattering rates of confined polar-optical phonons. Studies of optically pumped intersubband scattering in coupled quantum-well lasers have demonstrated that interface-phonon-assisted transitions are important in such structures; furthermore, simple analytical expressions have been derived that in...

We have observed coherent optical and acoustic phonon generation, which are strongly coupled to the charge-ordering sCOd transition in La1−xCaxMnO3 sx=0.5, 0.58d using femtosecond optical pump-probe spectroscopy. Coherent optical phonons, observed at low temperatures, disappear above the charge-ordering temperature TCO, while coherent acoustic phonons display the opposite behavior, disappearing...

The aim of this work is to describe the behavior of a device capable to generate high frequency (∼ THz) acoustic phonons. This device consists in a GaAs-AlGaAs double barrier heterostructure that, when an external bias is applied, produces a high rate of longitudinal optical LO phonons. These LO phonons are confined and they decay by stimulated emission of a pair of secondary longitudinal optic...

Fluorescence and phosphorescence phonon sidebands of isotopic mixed hexamethylbenzene crystals at 2°K are presented. The external phonons can be observed separately from the semi-internal (methyl torsion) ones. The nature of the electronic or vibronic state has observable but not drastic effects on the exciton-phonon coupling function. Likewise, the exciton delocalization is of minor importance...

The phonon structure of GaP quantum dots is studied using an atomistic potential model. The dot eigenmodes are obtained from a direct diagonalization of the dynamical matrix and classified using an efficient dual-space analysis method. Our calculations provide a theoretical explanantion for several experimental observations. ~1! Depending on the spatial localization, the phonon modes of dots ar...

Time dynamics of photoexcited electron-hole pairs is important for a number of technologies, in particular solar cells. We combined ultrafast pump-probe Raman scattering and photoemission to directly follow electron-hole excitations as well as the G-phonon in graphite after an excitation by an intense laser pulse. This phonon is known to couple relatively strongly to electrons. Cross-correlatin...

Ultrafast time-resolved reflectivity of a bismuth thin film evaporated on a silicon substrate is measured to investigate coherent phonons in bismuth. The reflectivity result is analyzed by a linear chirp approximation to obtain the time dependent frequencies of coherent phonons. Not only the optical modes are detected, which are generated by a combination of impulsive stimulated Raman scatterin...