In order to obtain a deeper insight into the inter-relation of magneti
sm and morphology we compare the properties of Fe films on Cu(100) and
Cu3Au(100) grown at different temperatures, using the magneto-optical
Kerr effect and scanning tunnelling microscopy. In Fe films on Cu3Au(
100) for both room- and low-temperature growth (RT and LT growth) neit
her an antiferromagnetic phase nor a good layer-by-layer growth, as fo
und for RT growth in Fe/Cu(100), was observed. The critical thickness
at which the spin reorientation transition from perpendicular to in-pl
ane easy axis starts, is found to be 3.5 ML for RT-grown Fe/Cu3Au(100)
as compared with 5.5 ML for the LT-grown films on both substrates.