Development of unusual magnetic anisotropy in Co-based trilayers

NiFe/Cu/Co trilayers have been prepared on 4 degrees tilt-cut Si (111) substrate by RF magnetron sputtering method. When a Cu(50 Angstrom) underlayer was deposited prior to the formation of the trilayer, NiFe and Co layers consisting of the trilayer developed in-plane magnetic anisotropy where the easy axes were perpendicular to each other. This unusual fact could be confirmed from the M-H curves and the corresponding R-H curves of the trilayers. When a small amount of Co was added to NiFe layer to form a NiFeCo/Cu/Co trilayer, the easy axes of NiFeCo and Co layers turned out to be aligned along the same direction so that perfectly square R-H curves could be obtained. In [NiFeCo(60 Angstrom)/Cu(25 Angstrom)/Co(30 Angstrom)]/Cu(50 Angstrom)/Si(111, 4 degrees tilt-cut) samples, 5.5% of MR ratio was obtained at room temperature, and the maximum and minimum MR values could be obtained at zero external magnetic field in the minor R-H curves. According to the R-H curves, it has been believed that NiFe/Cu/Co trilayers on 4 degrees tilt-cut Si (111) substrate are suitable for switching devices and NiFeCo/Cu/Co trilayers for a memory application. (C) 1997 American Institute of Physics.