CHARACTERISTICS OF NIFE CUNI MULTILAYER GMR SENSORS FOR VERTICAL GMR HEADS/

By using a novel NiFeCr buffer layer, a substantial improvement in a G MR ratio of 4.5% with a low saturation field of 19 Oe was obtained. Th e structure of all GMR multilayers was glass / NiFeCr [5nm] / NiFe [1. 7nm] / (CuNi[2.3nm] / NiFe[1.7nm])3 / Cr [2nm]. The change in sheet re sistance was 0.8 Ohms/square. Magnetoresistances, current density effe cts and transfer curves for 2, 1, and 0.5 micron trackwidth GMR sensor s of these structures are described. At a trackwidth of 0.5 mu m, maxi mum field sensitivity of 215 mu V/Oe was obtained with a sensor length of 2 mu m, a sense current of 3mA. No degradation in magnetoresistanc e of;sheet GMR was found after annealing at 270 degrees C. However, se nsor-size dependent thermal degradation was observed.