Abstract:
Measurements of the thermal conductivity (kxx) and the thermal Hall effect (kxy) in high magnetic fields in Y- and Bi-based high-T c superconductors are presented. We describe the experimental technique and test measurements on a simple metal (niobium). In the high-T c superconductors kxx and kxy increase below T c and show a maximum in their temperature dependence. kxx has contributions from phonons and quasiparticle (QP) excitations, whereas kxy is purely electronic. The strong increase of kxy below T c gives direct evidence for a strong enhancement of the QP contribution to the heat current and thus for a strong increase of the QP mean free path. Using kxy and the magnetic field dependence of kxx we separate the electronic thermal conductivity ( k xx el) of the CuO 2 -planes from the phononic thermal conductivity ( k xx ph). In YBa2Cu3O 7 - δ k xx el shows a pronounced maximum in the superconducting state. This maximum is much weaker in Bi2Sr2CaCu2O 8 + δ , due to stronger impurity scattering. The maximum of k xx el is strongly suppressed by a magnetic field, which we attribute to the scattering of QPs on vortices. An additional magnetic field independent contribution to the maximum of kxx occurs in YBa2Cu3O 7 - δ , reminiscent of the contribution of the CuO-chains, as determined from the anisotropy in untwined single crystals. Our data analysis reveals that below T c as in the normal state a transport (τ) and a Hall ( ) relaxation time must be distinguished: The inelastic (i.e. temperature dependent) contribution to τ is strongly enhanced in the superconducting state, whereas displays the same temperature dependence as above T c . We determine also the electronic thermal conductivity in the normal state from kxy and the electrical Hall angle. It shows an unusual linear increase with temperature.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received 23 August 2000
Rights and permissions
About this article
Cite this article
Zeini, B., Freimuth, A., Büchner, B. et al. Thermal conductivity and thermal Hall effect in Bi- and Y-based high-T c superconductors. Eur. Phys. J. B 20, 189–208 (2001). https://doi.org/10.1007/PL00011098
Issue Date:
DOI: https://doi.org/10.1007/PL00011098