Inelastic pulsed neutron scattering measurements on YBa2Cu3O6.95 single crystals indicate that the sample has a distinct a-b plane anisotropy in the oxygen vibrations. The Cu-O bond-stretching-type phonons, which are suspected to interact strongly with charge, are simultaneously observed along the a and b directions due to a 7-meV splitting arising from the orthorhombicity, even though the sample is twinned. The bond-stretching LO branch with the polarization along a (perpendicular to the chain) loses intensity beyond the middle of the zone, indicating branch splitting as seen in doped nickelates, with the second branch being located at 10 meV below. The mode along b has a continuous dispersion. These modes show temperature dependence, which parallels that of superconductive order parameter, suggesting significant involvement of phonons in the superconductivity of this compound.
J. Chung and T. Egami and R. J. McQueeney and M. Yethiraj and M. Arai and T. Yokoo and Y. N. Petrov and H. A. Mook and Y. Endoh and S. Tajima and C. D. Frost and F. Dogan, "In-Plane Anisotropy and Temperature Dependence of Oxygen Phonon Modes in YBa2Cu3O6.95," Physical Review B - Condensed Matter and Materials Physics, vol. 67, no. 1, pp. 014517-1-014517-9, American Physical Society (APS), Jan 2003.
The definitive version is available at http://dx.doi.org/10.1103/PhysRevB.67.014517
Materials Science and Engineering
Keywords and Phrases
barium; copper; oxygen; yttrium; anisotropy; conductance; crystal structure; dispersion; elementary particle; neutron scattering; oxygen affinity; polarization; temperature dependence; vibration
International Standard Serial Number (ISSN)
Article - Journal
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