Hall-effect studies in YBa2Cu3O7/PrBa2Cu3O7 superlattices

We measured the resistivity and the Hall coefficient RH in a series of YBa2Cu3O7/PrBa2Cu3O7 multilayers. We found no systematic change of the transport properties with decreasing layer thicknesses down to one unit cell. The resistivity and RH evaluated for the YBa2Cu3O7 layers are slightly higher than in bulk material, suggesting a small decrease of the carrier density in the multilayers. However, we observe no change in the Hall number 1/eRH when the thickness of the YBa1Cu3O7 layers decreases, so that the lowering of Tc observed in the superlattices cannot simply be related to a change in the carrier density. Furthermore, we find that the temperature dependence of RH is very similar to that of bulk materials.