Influence of the range of interactions in thin magnetic structures

The properties of thin magnetic structures are influenced by many length scales that reflect both generic physics and chemical detail. A striking example is the experimentally determined shift of the critical temperature as a function of film thickness. While all systems experience a pronounced suppression in the transition temperature with decreasing film thickness, the magnitude of this shift cannot be reconciled with established theoretical results. By means of detailed Monte Carlo simulations, we address this discrepancy by investigating a model with long range interactions. The model also captures other features of real thin magnets, such as an almost linear temperature dependence for the surface magnetization. Our results demonstrate that the behavior of thin magnetic structures arises from a competition of length scales dictated by their slab-like geometry, the presence of surface boundaries, and crucially, the range of the interactions present