PHASE-DIAGRAM FOR A MAGNETIC THIN-FILM WITH DIPOLAR INTERACTIONS AND MAGNETIC SURFACE ANISOTROPY

The phase diagram of a model thin him with long-range dipole-dipole in teractions and magnetic surface anisotropy is determined as a function of temperature and the surface anisotropy. We show that the model stu died here exhibits a reorientation transition in the absence of an exc hange interaction. Further we show that, unexpectedly,the transition i s from an in-plane phase to an out-of-plane phase with increasing temp erature, which is the opposite of the ferromagnetic case. The implicat ions of this study for the full phase diagram of a model which include s both the dipolar and exchange interactions are discussed.