EVOLUTION OF STRUCTURE AND MAGNETORESISTANCE IN GRANULAR NI(FE,CO) AGMULTILAYERS - DEPENDENCE ON MAGNETIC LAYER THICKNESS/

Structural and magnetoresistance results on annealed sputtered (Ni81Fe 19, Ni66Fe16Co18)/Ag granular multilayers are presented. Structural ev olution has shown that highly (111) textured, discontinuous layered st ructures can persist on annealing up to 400 degrees C. The average mag netic particle size is controlled by the annealing temperature and the initial magnetic layer thickness. No giant magnetoresistance was obse rved in the as-deposited films, while significant MR was found after a nnealing between 300 degrees C and 400 degrees C. Magnetoresistance ov er 30%, together with a small saturation field, was found at 4.2 K for a starting magnetic thickness of 4 Angstrom. Increasing the magnetic layer thickness to 20 Angstrom greatly improves the magnetic thermal s tability, and leads to high magnetoresistive sensitivities of up to 0. 35%/0e in a field of 10 Oe at room temperature. The magnetization hyst eresis, anisotropy, and magnetic interaction in such a granular multil ayer are also discussed.