  Dimensional effects in the critical properties of multilayer Heisenberg films
have been numerically studied by Monte Carlo methods. The effect of anisotropy
created by the crystal field of a substrate has been taken into account for
films with various thicknesses. The calculated critical exponents demonstrate a
dimensional transition from two-dimensional to three-dimensional properties of
the films with an increase in the number of layers. A spin-orientation
transition to a planar phase has been revealed in films with thicknesses
corresponding to the crossover region.
