The influence of superparamagnetic particle size distribution and ferromagnetic phase on GMR in melt spun Cu-Co granular alloys

Magnetic characteristics and structure of granular Cu/sub 90/Co/sub 10/ alloy were investigated in order to explain their relationship with electric transport properties. The annealed sample contains mainly Co-particles with sizes of a few nanometers and some much larger particles or agglomerations, which are not superparamagnetic. It is shown that the ferromagnetic phase contribution to the total magnetization (calculated applying the new, invented method) and differentiated surface to volume ratio of superparamagnetic particles are the main sources of the observed deviation of the magnetoresistance characteristics from that expected theoretically for superparamagnetic particles of equal size.