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

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 YBa 2 Cu 3 O y family with different kinds of deviation from stoichiometry: YBa 2 Cu 3 O y (y=6.37-6.91), YBa 2 Cu 3 - x Co x O y (x=0-0.3), Y 1 - x Ca x Ba 2 Cu 3 O y (x=0-0.25), and Y 1 - x Ca x Ba 2 - x La x Cu 3 O y (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=300 K for all the investigated samples, and in the case of a small absolute value Q becomes negative at low temperatures (T< 150 K). Deviations from stoichiometry influence the absolute value of Q, such as that of other transport coefficients, i.e., the Q(T= 300 K) value increases in the case of single substitutions (YBa 2 Cu 3 O y and YBa 2 Cu 3 - x Co x O y ) and changes insignificantly for double-substituted systems (Y 1 - x Ca x Ba 2 Cu 3 O y and Y 1 - x Ca x Ba 2 - x La x Cu 3 O y ).