Magnetoresistance in nanostructured Co-Ag prepared by mechanical alloying

Abstract

Fine cobalt and silver powders have been ball-milled to yield a granular solid of composition Co30Ag70 in the form of coarse powder. The material is an intimate mixture of grains of fcc Co in a silver matrix. The cobalt is in the single-domain size range, and the samples exhibit coercivity (0.07 T at 296 K) and unusual thermomagnetic effects, including field-induced unidirectional anisotropy. There is a large, isotropic negative magnetoresistance, which exceeds 10% at 4.2 K.