Low Temperature Magnetic Properties of Nanocrystalline Co-Nb-Cu-Si-B Alloys

Abstract

Co66Nb9Cu1Si12B12 metallic glass is used as a parent material for nanocrystalline magnets exhibiting low Curie temperature of the amorphous matrix (100-140 K). Precipitation of Co nanoparticles destroys the ferromagnetic ordering in the amorphous alloy and leads to a low-temperature cluster-glass state. At higher temperatures, the grains embedded in the paramagnetic matrix exhibit a superparamagnetic behaviour. In the fully crystallized state the magnetic properties of the material, composed of two crystalline phases with their Curie points above the room temperature, are mainly governed by the inter- and intra-phase magnetic interactions which lead to a preferential ferromagnetic ordering.