Magneto-optical properties of superparamagnetic CoPt alloy nanoparticles in the UV–visible range

Abstract

Superparamagnetic CoPt alloy nanoparticles were synthesized via a wet chemical method and exhibited intense magnetic circular dichroism (MCD) in the UV–visible range. The dissymmetry factor of MCD, gMCD, for the CoPt nanoparticles was 0.034 at room temperature in a magnetic field of ±1.6 T. The MCD responses may be due to plasmonic circular currents generated in the metallic CoPt nanoparticles by circularly polarized light. The responses were higher than those of the Co nanoparticles, likely due to the chemical stability and spin–orbit coupling.