Abstract:
The paper presents the results of the study and analysis of the temperature dependences of the Nernst–Ettingshausen coefficient, $Q$, in samples of the Y$_{1-x}$Ca$_x$Ba$_2$Cu$_{3-z}$Co$_z$O$_y$ system with different fixed cobalt content ($z$ = 0.25, 0.4) and varied calcium content ($x$ = 0–0.2). Using the values of the energy spectrum parameters in the studied samples, obtained earlier from the thermopower analysis, we performed a quantitative analysis of the experimental data and determined the values of the electron mobility and the degree of the dispersion law asymmetry. The influence of calcium on both the experimental $Q$($T$ = 300 K) value, and the values of the calculated charge-carrier parameters was observed to depend on the content of cobalt ions in the lattice. It is shown that both the type of dependence of these parameters on the calcium content and the differences in these dependences for the two studied sample series are caused by the peculiarities of the transformation of the YBa$_2$Cu$_3$O$_y$ energy spectrum under the influence of each of the studied impurities.
Keywords:high-temperature superconductors, doping, thermopower, energy spectrum.
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