Stray field and superconducting spin valve effect in La$_{0.7}$Ca$_{0.3}$Mn$O_3$/YBa$_2$Cu$_3$O$_{7-\delta}$ bilayers*

Electronic transport and magnetization measurements were performed on La$_{0.7}$Ca$_{0.3}$Mn$O_3$/YBa$_2$Cu$_3$O$_{7- \delta}$ (LCMO/YBCO) bilayers below the superconducting transition temperature. Two types of angular dependent magnetoresistance (MR) behavior were observed. One MR comes from the motion of weakly pinned vortices, which are induced by the out-of-plane stray field of the domain walls. The other MR depends on the relative angle between the magnetization at the LCMO/YBCO interface and the magnetization present in the interior of the LCMO layer and gives rise to the superconducting surface spin valve effect.