Vortex decoupling in LCMO/YBCO superlattices

We have investigated the effect of magnetic spacer on the coupling properties in YBa2Cu3O7/La0.3Ca0.7MnO3 superconducting/ferromagnet superlattices. Scaling analysis of the angular dependence of the magnetoresistance in the liquid state reveals a decoupled vortex liquid, as confirmed the magnetic field dependence of the activation energy for vortex motion. This result is discussed in terms of weak superconducting coherence along the c-direction resulting of pair breaking by spin polarized carriers.