Magnetotunneling in sputtered La0.7Ca0.3MnO3/Al2O3 multilayers

Magnetic multilayers in the form of [La0.7Ca0.3MnO3/Al2O3](n) + La0.7Ca0.3M nO3 were sputtered to study their magnetotunneling effect. Structural analy ses were performed by standard x-ray scattering, showing a well-defined sup erlattice. Both current perpendicular to plane (CPP) and current in plane ( CIP) methods were applied for the magnetoresistance measurements. The CPP v alue gives the tunneling effect through the thin insulating layers and show s a large low-field effect of about 60% for the trilayer junction and 50% f or the superlattice structure at 5 K, respectively. The CIP effect is about 30% (5 K) for all samples and is dominated here by the contribution of the intergrain tunneling effect within the La0.7Ca0.3MnO3 layers. (C) 2000 Ame rican Institute of Physics. [S0003-6951(00)02736-4].