Thermal conductivity of a BSCCO(2223) c-oriented tape: a discussion on the origin of the peak

Thermal conductivity and electrical resistivity measurements have been performed on a highly c-oriented (BiPb)(2)Sr2Ca2Cu2O10 tape in the range from 20 to 220 K. We analyse the experimental data in order to investigate the origin of the thermal conductivity maximum below T-c. Three different cases are considered: (1) the electron contribution to the thermal conductivity K-e, decreases as described by the Bardeen-Rickayzen-Tewordt model, while the phonon contribution. K-ph, is responsible for the peak (phonon approach); (2) K-e, described by means of the Kadanoff-Martin formalism, shows a peak while K-ph is a smooth decreasing function of decreasing temperature (electron approach); (3) both contributions present a peak (phonon + electron approach). The models we use involve some fundamental parameters, such as the amplitude of the energy gap, the Debye temperature, the mean dimension of the grains and the residual electron-impurity scattering rate. The best fit is obtained by the phonon + electron approach, but the phonon approach yields a more correct value for the energy gap. Finally, within the employed framework, we can exclude that only the electron peak by itself might account for our experimental data.