Spin-Polarized Electron Tunneling in Ni/Al₂O₃/Co Junction and Large Magnetoresistance of Ni/Co Double Layers

Abstract

The magnetic field dependence of the tunnel resistance of Ni/Al 2 O 3 /Co junctions and the resistance across the interfaces of Ni/Co junctions was studied. Both types of junctions showed the magnetic valve effect, in which junction resistances vary with the angle between the magnetizations of Ni and Co electrodes. For Ni/Co junctions, additional peaks were observed on the resistance versus magnetic field curves at the coercive fields of Co electrodes, suggesting the effect of magnetic domains formed in the junction area in the magnetization process. The relative change in resistance for the Ni/Co junction showed a large value of 16.4%.