Analysis of the charge transfer mechanism on (Ba1-xNdxCuO2+delta)(2)/(CaCuO2)(n) superconducting superlattices by thermoelectric power measurements

We have investigated the charge transfer mechanism in artificial superlattices by Seebeck effect measurements. Such a technique allows a precise determination of the amount of charge transferred on each CuO2 plane. A systematic characterization of thermoelectric power in (BaCuO2+delta)(2)/(CaCuO2)(n) and (Ba0.9Nd0.1CuO2+delta)(2)/(CaCuO2)(n) superlattices demonstrates that electrical charge distributes uniformly among the CuO2 planes in the Ca block. The differences observed in the Seebeck effect behavior between the Nd-doped and undoped superlattices are ascribed to the different metallic character of the Ba block in the two cases. Finally, the special role of structural disorder in superlattices with n=1 is pointed out by such analysis.