EPITAXY OF METASTABLE IRON PHASES

In this paper, Fe structures and magnetic properties in FeRu and FeIr superlattices are presented. Fe is grown on hexagonal surface lattices as Ru(0001), Ir (111), but also on rectangular or square ones as Ru ( 1122BAR), and Ir (100). On hexagonal lattices, the beginning of the gr owth is pseudomorphic in the plane of growth but Fe relaxes in its str ain bcc phase via Kurdjumov-Sachs (KS) coincidence. The pseudomorphic phase is shown to be non-magnetic at room temperature, as a moment app ears when relaxation occurs. In FeRu(1122BAR) superlattices, no KS rel axation occurs, and again 10 non-magnetic layers are observed. On the contrary, a small moment is observed for thin Fe layers on FeIr (100) superlattices. Fe is thus synthesized with body centered tetragonal st ructures with a c/a ratio varying from 1,26 to 1 (bcc). A rotation of the easy axis of magnetization as well as an increase of the magnetic moment is observed from out to in plane.