IN-SITU MCD MAGNETOMETRY IN THE ULTRATHIN LIMIT - FE ON CU(100)

By means of Magnetic Circular Dichroism in X-ray Absorption Spectrosco py we investigated the magnetic properties of fct Fe films stabilised by epitaxial growth on the Cu(100) surface. These are compared to bcc like Fe films. The films were characterised in situ by means of LEED, AES and XAS for order and cleanness. Low temperature (approximate to 5 0 K) and angle dependent measurements are reported for thicknesses aro und 3.5 (fct(5 x 1) phase) and 20 (bcc phase) monolayers. A much stron ger MCD response is obtained from the thinner films (perpendicular mag netisation). The MCD sum rules enabled us to determine the orbital and spin contributions to the magnetic moment for the two phases. The res ults are compared to theory.