MAGNETIC AND MAGNETOTRANSPORT PROPERTIES OF GRANULAR CU85FE15 PREPARED BY MECHANICAL ALLOYING

The magnetic and magnetotransport properties of granular Cu 85Fe15 prepared by mechanical alloying have been investigated. The sample was prepared by grinding fine powders of copper and iron in a high energy ball mill. Zero field cooled and field cooled susceptibilities showed a behavior that is typical of a superparamagnet. The blocking temperature TB of 20 K was determined from ac susceptibility. The magnetoresistance reached 5.5% at 4.5 K in a field of 5 T. It was increased to 7.6% after the sample was annealed at 300°C for 20 min. The hysteresis loop was measured for both magnetization and magnetoresistance. There was a clear correlation between the two. The magnetoresistance is due to the scattering associated with iron nanoparticles present in the samples and its dependence on particle size is discussed.