Scaling of the normal-state Nernst coefficient in doped Y-based high-temperature superconductors

Abstract

We report experimental data on the temperature and concentration dependencies of the Nernst coefficient Q in the normal state for several series of ceramic samples of the YBa2Cu3Oy family with different kinds of deviation from stoichiometry: YBa2Cu3Oy (y=6.37–6.91), YBa2Cu3−xCoxOy (x=0–0.3), Y1−xCaxBa2Cu3Oy (x=0–0.25), and Y1−xCaxBa2−xLaxCu3Oy (x=0–0.5), as well as their comparative qualitative analysis with respect to the other transport coefficients’ behavior. The Nernst coefficient is very small and positive at T=300K for all the investigated samples, and in the case of a small absolute value Q becomes negative at low temperatures (T<150K). Deviations from stoichiometry influence the absolute value of Q, such as that of other transport coefficients, i.e., the Q(T=300K) value increases in the case of single substitutions (YBa2Cu3Oy and YBa2Cu3−xCoxOy) and changes insignificantly for double-substituted systems (Y1−xCaxBa2Cu3Oy and Y1−xCaxBa2−xLaxCu3Oy).

Source-reported materials — not catalogue approval

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