Giant Magnetoresistance in NiFeCo/Cu Multilayers

NiFeCo/Cu multilayer films with NiFeCo buffer layers, prepared by rf magnetron sputtering, show a giant magnetoresistance (MR) effect which oscillates as a function of the Cu thickness. At the second peak of this oscillation, multilayer films have an MR ratio of 12% in fields as low as 50 Oe. The film structure and MR properties are stable with respect to annealing at temperatures up to about 300°C. A field sensitivity of about 0.4%/Oe was obtained over the minor loop of the MR curve, measured using a field in the hard-axis direction. The field sensitivity was almost constant up to a frequency of 1 MHz.