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Dynamic Stripes and Resonance in the Superconducting and Normal Phases of YBa2Cu3O6.5 Ortho-II Superconductor

C. Stock·W. J. L. Buyers·R. Liang·D. Peets·Z. Tun·D. Bonn·W. N. Hardy·R. J. Birgeneau
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Abstract

We describe the relation between spin fluctuations and superconductivity in a highly-ordered sample of YBaCu3O6.5 using both polarized and unpolarized neutron inelastic scattering. The spin susceptibility in the superconducting phase exhibits one-dimensional incommensurate modulations at low-energies, consistent with hydrodynamic stripes. With increasing energy the susceptibility curves upward to a commensurate, intense, well-defined and asymmetric resonance at 33 meV with a precipitous high-energy cutoff. In the normal phase, which we show is gapless, the resonance remains surprisingly strong and persists clearly in Q scans and energy scans. Its similar asymmetric spectral form above Tc=59 K suggests that incoherent superconducting pairing fluctuations are present in the normal state. On cooling, the resonance and the stripe modulations grow in well above Tc below a temperature that is comparable to the pseudogap temperature where suppression occurs in local and low-momentum properties. The spectral weight that accrues to the resonance is largely acquired by transfer from suppressed low-energy fluctuations. We find the resonance to be isotropically polarized, consistent with a triplet carrying ~2.6% of the total spectral weight of the Cu spins in the planes.

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C. Stock, W. J. L. Buyers, R. Liang, D. Peets, Z. Tun, D. Bonn, W. N. Hardy, R. J. Birgeneau. 2003-12-22. Dynamic Stripes and Resonance in the Superconducting and Normal Phases of YBa2Cu3O6.5 Ortho-II Superconductor. https://doi.org/10.1103/physrevb.69.014502

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