Abstract The covariant particle-vibration coupling model within the time blocking approximation is employed to supplement the Relativistic Random Phase Approximation (RRPA) with coupling to collective vibrations. The Bethe-Salpeter equation in the particle-hole channel with an energy dependent residual particle-hole (p-h) interaction is formulated and solved in the shell-model Dirac basis as we...

The Raman spectrum and particularly the Raman scattering intensities of monoclinic β-Ga2O3 are investigated by experiment and theory. The low symmetry of β-Ga2O3 results in a complex dependence of the Raman intensity for the individual phonon modes on the scattering geometry which is additionally affected by birefringence. We measured the Raman spectra in dependence on the polarization directio...

The thermal conductivities of individual single crystalline intrinsic Si nanowires with diameters of 22, 37, 56, and 115 nm were measured using a microfabricated suspended device over a temperature range of 20–320 K. Although the nanowires had well-defined crystalline order, the thermal conductivity observed was more than two orders of magnitude lower than the bulk value. The strong diameter de...

We describe a peculiar fine structure acquired by the in-plane optical phonon at the Gamma point in graphene when it is brought into resonance with one of the inter-Landau-level transitions in this material. The effect is most pronounced when this lattice mode (associated with the G band in graphene Raman spectrum) is in resonance with inter-Landau-level transitions 0 --> +, 1 and -, 1 --> 0, a...

We theoretically investigate dc electron resonant tunneling through an impurity state in a quantum well assisted by hot acoustical phonons. Numerical results for the tunneling current, obtained by nonequilibrium Green functions, reflect the hot-phonon-induced change in the spectrum and population of the impurity state. The induced change of the I-V characteristics has a typical two-peak form, w...

Nitinol (NiTi), the most widely used shape-memory alloy, exhibits an austenite phase that has yet to be identified. The usually assumed austenitic structure is cubic B2, which has imaginary phonon modes, hence it is unstable. We suggest a stable austenitic structure that " on average " has B2 symmetry (observed by x-ray and neutron diffraction), but it exhibits finite atomic displacements from ...

The phonon spectrum in a quantum crystal, where short-range correlations are important, is obtained by adapting the general relations between the onephonon response and the thermodynamic properties of an anharmonic crystal proposed by G6tze. Specifically, the one-phonon self-energy is obtained by requiring that the elastic constants obtained by the method of long waves equal those obtained as t...

We report reflectance measurements of single-crystal Sr2CuO2Cl2 over the frequency range between 30 cm and 40 000 cm. Using crystals of 10 mm to 100 mm thickness we were also able to perform transmittance measurements at frequencies below the lowest phonon mode as well as between the highest phonon mode and the charge-transfer gap. The measurements were done on the ~001! surface with ab polariz...

The interplay between the electron repulsion U and the Jahn-Teller electron-phonon interation E LR is studied with a large d model for the ferromag-netic state of the manganese oxides. These two interactions collaborate to induce the local isospin (orbital) moments and reduce the bandwidth B. Especially the retardation eeect of the Jahn-Teller phonon with the frequency is eeective to reduce B, ...