Size-dependent magnetic properties in Fe/Al multilayers

Morphological and magnetic properties of Fe/Al ultra-thin film multilayers are studied as a function of Fe layer thickness by means of transmission electron microscopy, conversion electron Mossbauer spectroscopy, alternating gradient force magnetometry and AC susceptometry. With decreasing iron layer thickness, aluminum diffusion causes a progressive loss of periodicity and the formation of particulate systems. The magnetic behavior progressively evolves from ferromagnetic to superparamagnetic.