W. Reichardt

Oxygen phonon branches in YBa2Cu3O7

We report results of inelastic neutron scattering measurements of phonon dispersions in optimally doped YBa2Cu3O6.95 and compare them with model calculations. The focus is on the in-plane oxygen bond-stretching phonon branches. The study of these modes is complicated by anticrossings with c-axis-polarized branches; such effects are interpreted through lattice-dynamical shell-model calculations. The in-plane anisotropy of the bond-stretching phonons was firmly ascertained from measurements on a detwinned sample. Studying the in-plane modes involving out-of-phase motion for the two Cu-O layers within a unit cell as well as those with in-phase motion was of great help for establishing a clear experimental picture. The measurements confirm that the in-plane oxygen bond-stretching phonon branches disperse steeply downwards from the zone center in both the a and the b directions indicating a strong electron-phonon coupling. For the b-axis-polarized bond-stretching phonons, there is an additional feature of considerable interest: a sharp local frequency minimum was found to develop on cooling from room temperature to T = 10 K at the wave vector q = 0.27 r.l.u..

Direct observation of the superconducting gap in phonon spectra.

We show that the superconducting energy gap 2Delta can be directly observed in phonon spectra, as predicted by recent theories. In addition, since each phonon probes the gap on only a small part of the Fermi surface, the gap anisotropy can be studied in detail. Our neutron scattering investigation of the anisotropic conventional superconductor YNi2B2C demonstrates this new application of phonon spectroscopy.

Electron-phonon coupling in the conventional superconductor YNi2B2C at high phonon energies studied by time-of-flight neutron spectroscopy.

We report an inelastic neutron scattering investigation of phonons with energies up to 159 meV in the conventional superconductor YNi(2)B(2)C. Using the sweep mode, a newly developed time-of-flight technique involving the continuous rotation of a single crystal specimen, allowed us to measure a four-dimensional volume in (Q, E) space and, thus, determine the dispersion surface and linewidths of the A(1g) (≈102 meV) and A(u) (≈159 meV) type phonon modes over the whole Brillouin zone. Despite of having linewidths of Γ=10 meV, A(1g) modes do not strongly contribute to the total electron-phonon coupling constant λ. However, experimental linewidths show a remarkable agreement with ab initio calculations over the complete phonon energy range, demonstrating the accuracy of such calculations in a rare comparison to a comprehensive experimental data set.

Lattice dynamics and electron-phonon coupling in Sr 2 Ru O 4 : Inelastic neutron scattering and shell-model calculations

The lattice dynamics in Sr

Oxygen phonon branches in detwinned YBa2Cu3O7

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Phonon Dispersions and Phonon Density-of-States in Copper-Oxide Superconductors

RuO

Phonons and electron-phonon coupling in YNi2B2C

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Ab initio phonon spectra from a supercell approach

has been studied by inelastic neutron scattering combined with shell-model calculations. The in-plane bond-stretching modes in Sr

Anomalous lattice dynamics of ruthenium

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Analysis of the local structure by single-crystal neutron scattering in La1.85Sr0.15CuO4

RuO