STRUCTURAL TRANSFORMATION AND SPIN-REORIENTATION TRANSITION IN EPITAXIAL FE CU3AU(100) ULTRATHIN FILMS/

The magnetic properties, morphology, and crystallographic structure ar e studied for Fe films on Cu3Au(100) grown at room and low temperature , using in situ magneto-optical Kerr effect, scanning tunneling micros copy, and electron diffraction techniques. At T = 160 K a spin-reorien tation transition from perpendicular to in-plane magnetization occurs in films with Fe coverages starting from a critical thickness of 3.5 a nd 5.5 ML for room-temperature and low-temperature growth, respectivel y. Close to the critical thickness we observe an fcc-bcc structural tr ansformation. The spin-reorientation transition is shown to be correla ted to this structural change. This correlation may be explained by a drastic reduction of the perpendicular anisotropy induced by the fcc-b cc structural transformation.