Dresden 2003 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 6: Postersitzung I (Amorphe- u. Tunnelsysteme, Niedrigdimensionale Systeme, Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter)
TT 6.29: Poster
Montag, 24. März 2003, 14:30–19:00, P2c, P2d
Vanishing of the nodal properties with temperature in the longitudinal thermal conductivity of YBa2Cu3O7−x — •Roberto Ocaña and Pablo Esquinazi — Department of Superconductivity and Magnetism, Universität Leipzig, D-04103 Leipzig
The angle dependence at different temperatures of the longitudinal thermal conductivity κxx(θ) 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 Tc. We found that the four-fold oscillation of κxx(θ) 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 Tc. 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.