Microstructures and magnetic properties of Co-Cu nanoparticles prepared by arc-discharge

摘要

The microstructures and magnetic properties of nanoparticles of immiscible system Co-Cu prepared by arc-discharge have been studied. The particles are about 20-30 nm in diameter showing core/shell structure. The cores are Co-Cu solutions, and the shell is copper oxide. The loop shift in the hysteresis loop indicates the existence of the exchange bias between ferromagnetic and antiferromagnetic components at low temperatures. A block temperature about 180K was observed for the Co-Cu nanoparticles. The thermal magnetization at low temperatures is not satisfied with Bloch's law.