LOW-FIELD GIANT MAGNETORESISTANCE IN DISCONTINUOUS MAGNETIC MULTILAYERS

Giant magnetoresistance of order 4%-6% has been observed in fields of 5-10 Oe at room temperature in annealed multilayers of Ni80Fe20/Ag pre pared by magnetron sputtering. For a wide range of NiFe and Ag thickne sses, no giant magnetoresistance was observed in the unannealed films. We attribute the appearance of giant magnetoresistance to a magnetost atic interlayer interaction that promotes antiparallel order of the mo ments in adjacent layers fostered by a breakup of the NiFe layers. We discuss the effects of variations in the underlayers, spacer thickness , and the sputtering process on the magnetoresistance. Our results sug gest that maximizing magnetoresistance and minimizing hysteresis requi re samples with continuous Ag layers that prevent contact between the NiFe layers and NiFe layers that are discontinuous but not too severly disrupted.