We present experimental data on the magnetic properties of atomically thin fcc ͑␥-phase͒ Fe films ͑1-6 atomic layer nominal thickness͒ epitaxially grown on Cu 84 Al 16 (100) obtained by linear magnetic dichroism in the angular distribution of Fe 3p core photoelectrons excited by linearly polarized synchrotron radiation. The sign and magnitude of the Fe 3p photoemission magnetic asymmetry indicates the onset of in-plane ferromagnetism at 2.5͑2͒ monolayer ͑ML͒ thickness of ␥-Fe. The Curie

more »

... ure is 288͑2͒ K for 4 ML thickness. The magnetic splitting of the Fe 3p mj core hole sublevels is 1.10͑2͒ eV, i.e., the same value as measured for a bcc-Fe͑100͒ surface where large surface and near-surface enhanced moments contribute. These results characterize the epitaxial ␥-Fe on Cu 84 Al 16 (100) as a high-spin ferromagnet for thickness up to 4 ML, with an average magnetic moment per iron atom of 2.5͑1͒ B . A phase transition occurs between 4 and 5 ML thickness: the magnetic order of the pseudomorphic ␥-Fe film decreases consistently with the breaking into two phases with the deeper layers in a low-spin and/or antiferromagnetic phase and surface restricted ferromagnetism, similar to the case of ␥-Fe/Cu͑100͒.