Investigation of the Extraordinary Phase Transition in Antiferromagnetic Thin Films: Computer Simulation

The extraordinary phase transition in antiferromagnetic thin films has been analyzed by computer simulation. The simulation has been performed using the Ising model and the Metropolis algorithm. Epitaxial films with a cubic lattice containing several monoatomic layers have been considered. The condition for the occurrence of surface and extraordinary phase transitions is the difference between the exchange integrals in the bulk of the film and on its surface. It is shown that the surface and extraordinary phase transitions occur in antiferromagnetic thin films containing no less than eight monoatomic layers. The extraordinary phase transition has been investigated for different film thicknesses. It is shown that the magnetic susceptibility near the phase transition line has a logarithmic dependence on the phase-transition temperature. The dependence of the critical indices of the logarithmic phase on the film thickness is obtained.