14 research outputs found
Inelastic x-ray scattering investigations of lattice dynamics in SmFeAsOF superconductors
We report measurements of the phonon density of states as measured with
inelastic x-ray scattering in SmFeAsOF powders. An unexpected
strong renormalization of phonon branches around 23 meV is observed as fluorine
is substituted for oxygen. Phonon dispersion measurements on
SmFeAsOF single crystals allow us to identify the 21 meV A
in-phase (Sm,As) and the 26 meV B (Fe,O) modes to be responsible for
this renormalization, and may reveal unusual electron-phonon coupling through
the spin channel in iron-based superconductors.Comment: 4 pages, 3 figures, submitted for SNS2010 conference proceeding
Gravitational hedgehog, stringy hedgehog and stringy sphere
We investigate the solutions of Einstein equations such that a hedgehog
solution is matched to different exterior or interior solutions via a spherical
shell. In the case where both the exterior and the interior regions are
hedgehog solutions or one of them is flat, the resulting spherical shell
becomes a stringy shell. We also consider more general matchings and see that
in this case the shell deviates from its stringy character.Comment: 11 page
Casimir energy of the massless scalar field on S-1 by the point-splitting method
We calculate the Casimir energy of the massless scalar field on a one dimensional Riemann sphere (S-1) using the point-splitting method. We consider the full space, half space and an arc of arbitrary radius. This problem is interesting since it may be solved analytically be several renormalization techniques
Probing the Coulomb interaction of PuCoGa5 by phonon spectroscopy
The phonon dispersion curves of the unconventional superconductor PuCoGa5 were studied by inelastic X-ray scattering at room temperature. The experimental data agree well with ab initio lattice dynamics calculations. An accurate theoretical description of the phonon spectrum is obtained only when a local Coulomb repulsion U approx. 3 âeV among 5f electrons is taken into account. This implies partial localization of the 5f electrons in this compound. A comparison made with the phonon spectrum of UCoGa5 suggests that the latter compound is better described with a fully itinerant f electrons model
Probing the Coulomb Interaction of PuCoGa by Phonon Spectroscopy
see attachmentJRC.E.6-Actinides researc
Probing the Coulomb Interaction of the Unconventional Superconductor PuCoGa5 by Phonon Spectroscopy
The discovery of superconductivity in the plutonium based intermetallic compound PuCoGa5 came as a surprise with regard to the high transition temperature Tc 18,5 K
for an actinide material [1].JRC.E.6-Actinides researc
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Inelastic X-ray Scattering Investigations of Lattice Dynamics in SmFeAsO1-xFy Superconductors
We report measurements of the phonon density of states as measured with inelastic x-ray scattering in SmFeAsO{sub 1-x}F{sub y} powders. An unexpected strong renormalization of phonon branches around 23 meV is observed as fluorine is substituted for oxygen. Phonon dispersion measurements on SmFeAsO{sub 1-x}F{sub y} single crystals allow us to identify the 21 meV A{sub 1g} in-phase (Sm,As) and the 26 meV B{sub 1g} (Fe,O) modes to be responsible for this renormalization, and may reaveal unusual electron-phonon coupling through the spin channel in iron-based superconductors