The Nernst–Ettingshausen Coefficient in the Normal Phase of Doped HTSCs of the YBa[sub 2]Cu[sub 3]O[sub y] System

Abstract

The temperature dependence of the Nernst-Ettingshausen coefficient Q(T) in the normal phase of doped HTSCs of the yttrium system was studied. The main features characterizing the behavior of this coefficient were revealed, and the character and mechanism of the effect that various nonisovalent substituents exert on the Q(T) dependence were analyzed. It is shown that the narrow-band model permits one not only to describe all the specific features observed in the Q(T) curves but also to perform a simultaneous quantitative analysis of the temperature dependences of four kinetic coefficients (the electrical resistivity and the Seebeck, Hall, and Nernst-Ettingshausen coefficients) with the use of a common set of model parameters characterizing the band structure and carrier system in the normal phase of an HTSC. This approach was employed to determine the carrier mobilities and the asymmetry of the dispersion curve in the systems studied (YBa2Cu3Oy, y = 6.37–6.91; YBa2Cu3−xCoxOy, x = 0–0.3; Y1−xCaxBa2Cu3Oy, x = 0–0.25; Y1−xCaxBa2−xLaxCu3Oy, x = 0–0.5) and to analyze the effect of the substitutions involved on the variation of these parameters.