MAGNETOOPTIC MEASUREMENTS ON ULTRATHIN GD FILMS ON Y

We report on magnetooptic measurements on thin Gd films (3 Angstrom le ss than or equal to d(Gd) less than or equal to 1000 Angstrom) grown o n an Y buffer layer and covered with a 100-Angstrom Y protective top l ayer. 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 gro wth conditions on the magnetic properties was examined. For films prep ared at 300 degrees C, ferromagnetic phase transitions have been obser ved for nominal film thicknesses down to about one monolayer of Gd. Th e thickness dependence of the Curie temperature T-C follows a power la w with an exponent lambda = 1.6 close to the theoretical value for a 3 D-Ising ferromagnet.