QUENCHING OF GIANT MAGNETORESISTANCE BY INTERFACE ROUGHENING AND ALLOYING IN ANNEALED [(NIXFE1-X)(Y)AU-1-Y] AU MULTILAYERS/

Antiferromagnetically coupled permalloy/Au multilayers display giant m agnetoresistance (GMR) with large changes in resistance in very low fi elds. We show that thermal annealing of such structures, exhibiting GM R, leads to a quenching of the magnetoresistance. The detailed structu re of the permalloy/Au interfaces has been probed using high-resolutio n cross-section transmission electron microscopy. On annealing, the Au layers interdiffuse into the permalloy layers, which leads both to ro ugher permalloy/Au interfaces and to ''thinner'' Au spacer layers. We infer that the latter results in ferromagnetic coupling of the permall oy layers, which accounts for the reduced GMR. (C) 1996 American Insti tute of Physics.