Physica C: Superconductivity 408-410, 716 (2004)
Proceedings of the International Conference on Materials and Mechanisms of Superconductivity. High Temperature Superconductors VII — M2SRIO

[This work was supported by the Deutsche Forschungsgemeinschaft under DFG ES 86/4-3]

Ocaña, R.; Esquinazi, P.

Abstract

Longitudinal (κ_xx) and transverse (Hall) (κ_yy) measurements of the thermal transport inYBa₂Cu₃O₇ crystals for magnetic fields parallel and perpendicular to the c-axis at different angles with respect to the heat current direction show: (1) the temperature dependence of the inelastic scattering rate of quasiparticles (QP) follows ~ T⁴ at 0.2 < T/T_c ≤ 1,independently of the method used to estimate the electronic contribution; (2) for parallel fields, fourfold and twofold angular patterns were obtained for κ_xx and κ_xy at T < 20 Kwhereas at higher T the fourfold pattern vanishes and transforms into a one-fold oscillation; (3) two processes, i.e. Andreev scattering and Doppler shift, appear to determine the scattering of the QP by vortices. The overall results support a d-wave symmetry for the superconducting order parameter up to T_c.