Giant magnetoresistance effect in Fe56Co30Ni14/Cu

Giant magnetoresistance (MR) effect has been investigated for Fe-rich FeCoNi(1.5 nm)/Cu(0.8 to 2.6 nm) multilayers deposited by rf magnetron sputtering method on MgO(100) or glass substrates with Fe buffer layers. The MR ratio, the antiferromagnetic coupling strength and the film structure were examined for the multilayers with the magnetic layers of Fe56Co30Ni14. The multilayers exhibit oscillatory MR as a function of Cu thicknesses in the same manner as Fe/Cu multilayers. The multilayer of glass/Fe/[Fe56Co30Ni14(1.5 nm)/Cu(1.3 nm)](20) exhibited a large MR ratio of 24% at room temperature and 40% at 77 K. After annealing at 250 degrees C, the MR ratio became still larger, 40% at RT and 67% at 77 K, which are comparable to those of Co/Cu multilayers.