Giant Magnetoresistance and Madnetic Precipitates in Melt Spun Cu₈₈Co₁₂ Alloy

The melt spun Cu₈₈Co₁₂ has obvious giant magnetoresistance (GMR) after annealed at 450°C for 0.5h. By means of filed ion microscope with atom probe (FIM-AP), the spherical Co precipitates were clearly observed in this alloy for the first time. The average diameter of the particles is about 1.7nm in the specimen annealed at 450°C for 2h, which has the highest GMR of 30.7% at 1.5K. By using both persistence size method and direct measurement method on micrographs from FIM, the size distribution of the Co particles was determined. These results are very useful for testing the present theory on the relationship between GMR and microstructure.