Analysis of the charge transfer mechanism on (Ba1-xNdxCuO2+d)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 (BaCuO 2+?)2/(CaCuO2)n and (Ba 0.9Nd0.1CuO2+ ?)2/(CaCuO 2)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.