Related papers: Kohn Anomaly in MgB2 by Inelastic X-Ray Scattering
Two-phonon contributions to meV-resolved inelastic x-ray scattering spectra of MgB2 at 300K are identified, in good agreement, in both intensity and energy, with a harmonic calculation using the force constant matrix from ab-inito LDA…
We measure phonon dispersion and linewidth in a single crystal of MgB_2 along the Gamma-A, Gamma-M and A-L directions using inelastic X-Ray scattering. We use Density Functional Theory to compute the effect of both electron-phonon coupling…
Temperature dependent Raman scattering studies in polycrystalline MgB2(10<T<300 K)reveal that the E2g phonon does not experience any self energy renormalization effect across the superconducting critical temperature Tc ~ 40 K. In contrast,…
We report high-resolution inelastic x ray scattering measurements of the acoustic phonons of URu2Si2. We observe minimal change in the phonon structure upon entering the Hidden Order phase. At all temperatures, the longitudinal acoustic…
We study anharmonic effects in MgB2 by comparing Inelastic X-ray and Ramanscattering together with ab-initio calculations. Using high statistics and high q resolution measurements we show that the E2g mode linewidth is independent of…
The paper presents detailed Raman scattering study of the unusually broad E2g phonon mode in MgB2 crystal. For the first time, it is shown by the polarized Raman scattering on few-micron-size crystallites with natural faces that the…
We present a Raman scattering study of the E2g phonon anharmonicity and of superconductivity induced self-energy effects in MgB2 single crystals. We show that anharmonic two phonon decay is mainly responsible for the unusually large…
We report inelastic neutron scattering measurements of the phonon density-of-states in Mg11B2, which has a superconducting transition at 39.2 K. The acoustic phonons extend in energy to 36 meV, and there are highly dispersive optic branches…
The effect of pressure on optical phonon frequencies of MgB$_2$ has been calculated using the frozen-phonon approach based on a pseudopotential method. Gr\"uneisen parameters of the harmonic mode frequencies are reported for the…
Room temperature Raman scattering measurements have been carried out on well characterized samples of MgB2-xCx. The Raman line corresponding to the E2g phonon mode shows progressive hardening from 620 cm-1 in pristine MgB2 to 775 cm-1 in…
We compute the anharmonic shift of the phonon frequencies in MgB2, using density functional theory. We explicitly take into account the scattering between different phonon modes at different q-points in the Brillouin zone. The shift of the…
We report the boron isotope effect on the E2g phonon mode by micro-Raman spectroscopy on the ternary Mg1-xAlxB2 system, synthesized with pure isotopes 10B and 11B. The isotope coefficient on the phonon frequency is near 0.5 in the full…
We report magnetoresistance (MR) measurements on MgB2 and the corresponding full account from ab-initio calculations; we suggest that this combination can be a useful tool to probe electron- phonon coupling. We obtain good quantitative…
Raman spectra of the MgB2 ceramic samples were measured as a function of pressure up to 32 GPa at room temperature. The spectrum at normal conditions contains a very broad peak at ~590 cm-1 related to the E2g phonon mode. The frequency of…
The phonon-mode decomposition of the electron-phonon coupling in the MgB2-like system Li_{1-x}BC is explored using first principles calculations. It is found that the high temperature superconductivity of such systems results from extremely…
Superconducting MgB$\_2$ shows an E$\_{2g}$ zone center phonon, as measured by Raman spectroscopy, that is very broad in energy and temperature dependent. The Raman shift and lifetime show large differences with the values elsewhere in the…
We report inelastic light scattering experiments on CaFe_2As_2 in the temperature range of 4 to 290 K. In in-plane polarizations two Raman-active phonon modes are observed at 189 and 211 cm-1, displaying A_1g and B_1g symmetries,…
We report Raman spectra and synchrotron x-ray diffraction measurements of lattice parameters of polycrystalline MgB2 under hydrostatic pressure conditions up to 15 GPa. An anomalously broadened Raman band at 620 cm-1 is observed that…
An anisotropic lattice anomaly near the superconducting transition temperature, Tc, was observed in MgB2 by high-resolution neutron powder diffraction. The a-axis thermal expansion becomes negative near Tc, while the c-axis thermal…
Recent first principles calculations of the phonon dispersion curves in MgB_2 have suggested the presence of anomalies in some of the curves, particularly in the longitudinal acoustical (LA) branch in the Gamma to A direction. Similar…