There are several classes of coherent phonons whose generation mechanisms are completely different: impulsive stimulated Raman scattering, Brillouin oscillations, and coherent longitudinal-acoustic-phonon Bragg reflection. All of these are investigated in Si/SiGe superlattices using a picosecond ultrasonics technique at room temperature. Bragg reflection for a single vibrational mode is related...

We measured the dispersion of the graphite optical phonons in the in-plane Brillouin zone by inelastic x-ray scattering. The longitudinal and transverse optical branches cross along the Gamma-K as well as the Gamma-M direction. The dispersion of the optical phonons was, in general, stronger than expected from the literature. At the K point the transverse optical mode has a minimum and is only a...

ARP Angle Resolved Photoemission DFT Density Functional Theory FT Frustrated Translation HATOF He Atoms Time of Flight HREELS High Resolution Electron Energy Loss Spectroscopy IRAS Infrared Reflection Absorption Spectroscopy L Longitudinally polarised mode LDA Local Density Approximation LDM Lattice Dynamical Model LEED Low Energy Electron Diffraction ML Monolayer NEXAFS Near Edge X-rays Absorp...

A microscopic theory for the coupling of intrinsic Josephson oscillations and dispersive phonon branches in layered superconductors is developed. Thereby the effect of phonons on the electronic c-axis transport enters through an effective longitudinal dielectric function. This coupling provides an explanation of recently observed subgap resonances in the Idc-Vdc-curve of anisotropic cuprate sup...

A model for calculating the lattice thermal conductivity in semiconductor thin films and nanowires is developed. It is based on the solution of phonon Boltzmann equation and takes into account phonon dispersion modification due to confinement effects and non-equilibrium phonon redistribution. Phonon spatial confinement at the structure boundaries leads to modification of the acoustic phonon dis...

I apply the newly developed dynamical cluster approximation (DCA) to the calculation of the electron and phonon dispersions in the two dimensional Holstein model. In contrast to previous work, the DCA enables the effects of spatial fluctuations (non-local corrections) to be examined. Approximations neglecting and incorporating lowest-order vertex corrections are investigated. I calculate the ph...

I apply the newly developed dynamical cluster approximation (DCA) to the calculation of the electron and phonon dispersions in the two dimensional Holstein model. In contrast to previous work, the DCA enables the effects of spatial fluctuations (non-local corrections) to be examined. Approximations neglecting and incorporating lowest-order vertex corrections are investigated. I calculate the ph...

I apply the newly developed dynamical cluster approximation (DCA) to the calculation of the electron and phonon dispersions in the two dimensional Holstein model. In contrast to previous work, the DCA enables the effects of spatial fluctuations (non-local corrections) to be examined. Approximations neglecting and incorporating lowest-order vertex corrections are investigated. I calculate the ph...