GIANT MAGNETORESISTANCE OF DILUTE CU(CO) GRANULAR FILMS

Granular films of Cu (Co) with Co concentrations from 5.4% to 12% in t he as-deposited form had magnetization showing about 60% of the Co as ferromagnetic particles and exhibited giant magnetoresistance (MR) of about 20% at 4.2 K. Annealing at approximately 310-degrees-C increased the MR to 40% and also increased the saturation magnetization indicat ing additional Co precipitation. At higher annealing temperatures MR d ecreased to 1%. The Zhang theoretical model involving polarized conduc tion electron scattering at particle interfaces seems to give a reason able description of our results including the quadratic behavior of MR vs [M(H)]2 and MR vs [M(s)(T)]2.