Influence of temperature on the nodal properties of the longitudinal thermal conductivity of YBa${}_2$Cu${}_3$O${}_{7-x}$

Abstract

The angle dependence at different temperatures of the longitudinal thermal conductivity ${\kappa }_{xx}(\theta )$ in the presence of a planar magnetic field is presented. In order to study the influence of the gap symmetry on the thermal transport angular scans were measured up to a few Kelvin below the critical temperature $T_c$. We found that the four-fold oscillation of ${\kappa }_{xx}(\theta )$ vanishes at $T>20$K and transforms into a one-fold oscillation with maximum conductivity for a field of 8 T applied parallel to the heat current. Nevertheless, the results indicate that the d-wave pairing symmetry is the main pairing symmetry of the order parameter up to $T_c$. Numerical results of the thermal conductivity using an Andreev reflection model for the scattering of quasiparticles by supercurrents under the assumption of d-wave symmetry provide a semiquantitative description of the overall results.

7 figures, EPJ B (in press, 2003)

References in corpus (3)

• Novel anisotropy in the superconducting gap structure of Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} probed by quasiparticle heat transport
• Thermal Conductivity Tensor in YBa${}_2$Cu${}_3$O${}_{7-x}$: Effects of a Planar Magnetic Field
• Angle Dependence of the Transverse Thermal Conductivity in YBa${}_2$Cu${}_3$O${}_7$ single crystals: Doppler Effect vs. Andreev scattering