THERMAL-BEHAVIOR AND MAGNETIC-PROPERTIES OF FE/AL2O3 MULTILAYERS

We have deposited iron/alumina multilayers on saphhire wafers using RF magnetron sputtering. In the aim to study their thermal behaviour, multilayers have been annealed in a tubular furnace under a controlled atmosphere and characterized by x-ray diffraction, room-temperature bulk magnetization and Fe-57 Mossbauer spectroscopy. Without treatment, Fe/Al2O3 multilayers consist of alternating amorphous alumina and polycrystalline iron. For thermal treatments above 773 K, we observe the coexistence of Fe2+, and metallic BCC and FCC Fe. The presence of these phases is related to the respective thicknesses of the Fe and Al2O3 layers for three different samples. Competition between the interfacial and shape magnetic anisotropy is found to be strongly dependent on the presence of FCC iron.