Magnetooptic measurements on ultrathin Gd films on Y

We report on magnetooptic measurements on thin Gd films (3 Åd _Gd 1000 Å) grown on an y buffer layer and covered with a 100-Å Y protective top layer. Measurements were carried out in the temperature range from 2 to 300 K and for magnetic field up to 0.3 T. The effect of different growth conditions on the magnetic properties was examined. For films prepared at 300°C, ferromagnetic phase transitions have been observed for nominal film thicknesses down to about one monolayer of Gd. The thickness dependence of the Curie temperatureT _C follows a power law with an exponent =1.6 close to the theoretical value for a 3D-Ising ferromagnet.