Abstract
γ-Fe 2 O 3 nanoparticles were coated with a Cu shell in situ during synthesis. An interfacial monolayer of CuO in the Cu-coated -Fe 2 O 3 nanoparticles was discovered that stabilized the disordered surface spins of -Fe 2 O 3 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 -Fe 2 O 3 nanoparticles 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 -Fe 2 O 3 nanomagnetism. Increasing the Cu shell thickness also increased the total Fe magnetism of the nanoparticles. © 2012 IOP Publishing Ltd.