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, mu ltilayers have been annealed in a tubular furnace under a controlled a tmosphere and characterized by x-ray diffraction, room-temperature bul k magnetization and Fe-57 Mossbauer spectroscopy. Without treatment, F e/Al2O3 multilayers consist of alternating amorphous alumina and polyc rystalline iron. For thermal treatments above 773 K, we observe the co existence of Fe2+, and metallic BCC and FCC Fe. The presence of these phases is related to the respective thicknesses of the Fe and Al2O3 la yers for three different samples. Competition between the interfacial and shape magnetic anisotropy is found to be strongly dependent on the presence of FCC iron.