THE EXPERIMENTALLY DETERMINED THIN-FILM LIMIT TO THE GINZBURG-LANDAU MODEL OF THIN-FILM MAGNETISM

Experimental evidence is provided for terbium overlayers on Fe(100) de monstrating that the Ginzburg-Landau model fails for ferromagnetic ter bium at submonolayer coverages. This failure of mean field theory to s uccessfully describe experimental data occurs quite close to the site percolation limit of 0.5 to 0.59 monolayers, and the coverage at which appreciable second layer adsorption occurs in a simultaneous multilay er growth model. For thicker films, modeling of the experimental data suggests that the thickness dependence of the magnetization depends ve ry strongly upon temperature, as expected.