Increased surface spin stability in γ-Fe2O3 nanoparticles with a Cu shell

Abstract

γ-Fe2O3 nanoparticles were coated with a Cu shell in situ during synthesis. An interfacial monolayer of CuO in the Cu-coated γ-Fe2O3 nanoparticles was discovered that stabilized the disordered surface spins of γ-Fe2O3 nanoparticles. Element-specific x-ray absorption spectroscopy at the L-edges for Cu and Fe indicated the magnetic moment of the Cu in the shell interacted with the γ-Fe2O3 nanoparticle’s surface magnetic moments. This exchange interaction between the Fe and Cu at the interface permitted an overall Cu moment in CuO (an antiferromagnet typically) that altered the γ-Fe2O3 nanomagnetism. Increasing the Cu shell thickness also increased the total Fe magnetism of the nanoparticles.