Correlation between magnetism and structure in ultrathin Fe/Cu3Au(001) films

We have studied the correlation between the magnetic properties and the structure of ultrathin ferromagnetic Fe/Cu3Au001 films for thicknesses up to 15 Å. We have found that two different face centered tetragonal structural phases coexist within the film in the thickness range 5–15 Å. The coexistence of the two structural phases induces an anomalous thickness dependence of the Curie temperature of the films. We ascribe this thickness dependence to a difference in the exchange coupling between the two phases. The irreversible modifications of the magnetic properties of the films after a mild thermal treatment are discussed on the basis of the corresponding changes of the structure and the morphology