Interface-Engineered Control of Fe/Cu Thin Film Magnetism

We show that the magnetism of Fe/Cu nanostructured thin films can be controlled by adjusting an interfacial FeCu alloy formed during in situ ion-beam bombardment of the Fe atoms, promoting intermixing between the Fe and Cu, forming an FeCu alloy. This intermixing results in prominent changes to the inter- and intracrystallite interactions which govern the magnetism. With increased interfacial alloy content, the films were modified from a multilayer to a dispersion morphology. This control over increased disorder tuned the magnetic interactions, such as enabling the coexistence of superparamagnetism of Fe nanocrystallites and magnetic ordering of the FeCu component so that a film’s coercivity increased with warming near TC.