MONTE-CARLO CALCULATIONS ON THE DIMENSIONAL CROSSOVER OF THIN ISING FILMS

The dimensional crossover of thin Ising films from 2D behaviour at tem peratures near T-c to 3D behaviour at lower temperatures is investigat ed in a extended Monte Carlo (MC) cluster simulation for various film thicknesses. We were able to observe the dimensional crossover directl y from effective critical exponents beta(eff), gamma(eff) which we hav e calculated from the MC data, The crossover occurs in a rather large temperature interval below T-c. A comparison with recent experimental investigations on thin nickel films shows a satisfactory similarity to the simple Ising model.