Phase Transition in Ultrathin Films

Within the frame of average spin the dependence of Neel temperature of ultrathin antiferromagnetic film for FCC crystalline lattice on its thickness and the concentration of magnetic atoms has been defined. The λ values calculated by us are close to experimental values obtained for the films СoO/SiO2. The increasing of thickness leads to decreasing of the critical concentration down to the value equal to percolation threshold.