GIANT MAGNETORESISTANCE AND HIGH-SENSITIVITY IN ANNEALED NIFECO AG MULTILAYERS/

We report giant magnetoresistance in annealed NiFeCo (2 nm)/Ag (3.3 nm ) multilayers. For all samples, post-deposition annealing was necessar y for the observation of GMR analogous to the NiFe/Ag discontinuous mu ltilayer system. The GMR ratio and field sensitivity varied widely as a function of annealing from temperatures between 300 and 400 degrees C. A high MR ratio of 6.3% and field sensitivity of 11.3%(kA/m) (0.9%/ Oe) were observed for a seven bilayer sample annealed to 350 degrees C . In general, NiFeCo/Ag multilayers produced greater MR responses and field sensitivities than comparably annealed NiFe/Ag multilayers. NiFe Co/Ag multilayers, however, display more hysteresis than NiFe/Ag multi layers and lack a zero-crossing saturation magnetostriction versus ann ealing temperature. Multilayer deposition in a magnetic field severely degrades MR performance since it prevents the magnetostatic antiparal lel alignment between magnetic grains which occurs in the absence of a n applied magnetic field following sample annealing. (C) 1996 American Institute of Physics.