Magnetoresistance and magnetic properties of NiFe/oxide/Co junctions prepared by magnetron sputtering

NiFe/oxide/Co junctions were fabricated by magnetron sputtering for studies of polarized electron transport across the insulating barrier. Al2O3, Al-Al2O3, and MgO insulating barriers were prepared with junction resistances from 0.5 to 116 Ω. The I-V characteristics at room temperature are linear. For low barrier resistance, the magnetoresistance of the structure is dominated by the anisotropic magnetoresistance of the ferromagnetic electrodes. For the higher barrier resistances, a different magnetoresistance effect is observed, which is tentatively related to tunneling or spin-valve effects across the insulating junction.