SIZE EFFECTS AND GIANT MAGNETORESISTANCE IN UNANNEALED NIFE AG MULTILAYER STRIPES/

We have observed giant magnetoresistance (GMR) in unannealed NiFe/Ag m ultilayer thin-film stripes, Rectangular stripes having constant thick ness and a constant 11:1 length-to-width aspect ratio, but varying wid ths down to 0.5 mu m, were measured. Two types of multilayer configura tions were tested, a system of five NiFe/Ag bilayers with 5.5-nm-thick Ag spacer layers, and a system of nine bilayers with 4.4-nm-thick Ag layers. In contrast to the characteristic of annealed NiFe/Ag multilay er stripes, the unnannealed stripes produced increasing GMR ratios for decreasing stripe sizes, with the 0.5-mu m-wide stripe of the five-bi layer system exhibiting a Delta R/R of 2.5%. Barkhausen noise and resp onse broadening also increased with decreasing stripe size, however. T he results are discussed in terms of magnetostatic coupling of the NiF e layers within the stripes.