Magnetoresistance in La0.7Ca0.3MnO3–YBa2Cu3O7 F/S/F trilayers

We report large magnetoresistance in ferromagnet/erconductor/ferromagnet structures made of La0.7Ca0.3MnO3 and YBa2Cu3O7 at temperatures along the resistive transition. We find that the magnetoresistance phenomenon is independent on the orientation of electric current versus field. Furthermore, the effect is also independent on the sweep rate of the magnetic field. This excludes interpretations in terms of spontaneous vortices or anisotropic magnetoresistance of the ferromagnetic layers and supports the view that the magnetoresistance phenomenon originates at the spin-dependent transport of quasiparticles transmitted from the ferromagnetic electrodes into the superconductor.