title: Highly anisotropic anomaly in the dispersion of the copper-oxygen bond-bending phonon in superconducting YBa2Cu3O7 from inelastic neutron scattering.
abstract: Motivated by predictions of a substantial contribution of the "buckling" vibration of the CuO(2) layers to d-wave superconductivity in the cuprates, we have performed an inelastic neutron scattering study of this phonon in an array of untwinned crystals of YBa(2)Cu(3)O(7). The data reveal a pronounced softening of the phonon at the in-plane wave vector q=(0,0.3) upon cooling below ~105 K, but no corresponding anomaly at q=(0.3,0). Based on the observed in-plane anisotropy, we argue that the electron-phonon interaction responsible for this anomaly supports an electronic instability associated with a uniaxial charge-density modulation and does not mediate d-wave superconductivity.
authors: Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany.
authors: M
authors: M
authors: Raichle
authors: D
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authors: Reznik
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authors: Lamago
authors: R
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authors: Heid
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authors: Li
authors: M
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authors: Bakr
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authors: Ulrich
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authors: Hinkov
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authors: Hradil
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authors: Lin
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authors: Keimer