Unified Understanding of Giant Magnetoresistance Effect and Magnetization in Granular Films with Two-Particle Size Distribution

The giant magnetoresistance (GMR) effect and magnetization curves of Cu₈₀Co₂₀ granular thin films are studied and measured in a superparamagnetism temperature (180K). The correlation between the GMR effect and the magnetization is analysed in a unified framework. These two independent properties are fitted by assuming that there are two size distributions in the Co nano-particle population. Under an assumption, good fittings are achieved for both the GMR and the magnetization, using the minimal number of parameters. The obtained average particle sizes for the smaller and larger particles are 1.0 nm and 2.8 nm, respectively. In fitting the magneto-transport, a power scaling relationship with the particle size for each size population is proposed, and the fitted results reveal that a certain degree of magnetic bulk scattering is present in larger particles.