An inelastic pulsed neutron scattering study was performed on the dependence of the dispersion and spectral intensity of the in-plane Cu-O bond-stretching LO phonon mode on doped charge density. The measurements were made in the time-of-flight mode with the multiangle position sensitive spectrometer of the ISIS facility on single crystals of YBa2Cu3O6+x (x=0.15, 0.35, 0.6, 0.7, and 0.95). The focus of the study is the in-plane Cu-O bond-stretching LO phonon mode, which is known for strong electron-phonon coupling and unusual dependence on composition and temperature. It is shown that the dispersions for the samples with x=0.35, 0.6, and 0.7 are similar to the superposition of those for x=0.15 and 0.95 samples, and cannot be explained in terms of the structural anisotropy. It is suggested that the results are consistent with the model of nanoscale electronic phase separation, with the fraction of the phases being dependent on the doped charge density.
F. Stercel et al., "Composition Dependence of the In-Plane Cu-O Bond-stretching LO Phonon Mode in YBa₂Cu₃O₆₊x," Physical Review B, American Physical Society (APS), Jan 2008.
The definitive version is available at http://dx.doi.org/10.1103/PhysRevB.77.014502
Materials Science and Engineering
National Science Foundation (U.S.)
Keywords and Phrases
Bonds (Chemical); Phase Separation; Yttrium Compounds; Barium compounds; Electron-phonon interactions; High temperature superconductors; Neutron - diffraction
Article - Journal
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