Spatially modulated magnetic structures in thin films

The axial next-nearest neighbour Ising (ANNNI) model is studied for thin films of up to $L=10$ layers, with a distinct phase diagram for each film thickness. The systematics of the ordered phases, as obtained from mean-field theory, Monte Carlo simulations, and low temperature expansions, is discussed. Results are compared to those for the ANNNI model in the limit $L \longrightarrow \infty$.