Reversal magnetoresistance effect in ferromagnet/superconductor/ferromagnet/antiferromagnet heterostructure

The oxide heterostructure consisting of La0.7Sr0.3MnO3/YBa2Cu3O7-delta/La0.7Sr0.3MnO3/La0.33Ca0.67MnO3 is fabricated by using the technique of pulsed laser deposition. The magnetoresistance (MR) for the system is investigated in the region of mixed vortex state near the onset temperature of superconducting transition. The present experimental results indicate a reversal variation in MR that is observed with increasing temperature in the system, implying the competition between a positive MR of YBa2Cu3O7-delta and a negative MR of La0.7Sr0.3MnO3. Furthermore, our analysis further suggests that the large MR peaks are mainly caused by spin-dependent interface scattering, which depends on the relative orientation of magnetization in two ferromagnetic layers. And it is proved that the superconductivity is an essential factor for the large positive MR in the artificial heterostructure system. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3103330]