GIANT MAGNETORESISTANCE AT LOW FIELDS IN DISCONTINUOUS NIFE-AG MULTILAYER THIN-FILMS

A series of sputtered multilayers of Ni80Fe20-Ag was prepared to exami ne the giant magnetoresistance effect before and after annealing. For a wide range of NiFe and Ag thicknesses, no giant magnetoresistance wa s observed in the unannealed films. After annealing, a large, negative magnetoresistance was observed of order 4 to 6% in applied fields of order 5 to 10 oersteds at room temperature. The appearance of giant ma gnetoresistance is concurrent with the breakup of the NiFe layers, whi ch is attributable to a magnetostatic interaction that favors local an tiparallel alignment of the moments in adjacent layers. These structur es may be of significant practical importance as sensors that require large changes in resistance at low fields, such as magnetoresistive he ads used in magnetic recording systems.