We demonstrate that the reorientation transition from out-of-plane to in-plane magnetization with decreasing temperature as observed experimentally in Ni-films on Cu(001) can be explained on a microscopic basis. Using a combination of mean field theory and perturbation theory, we derive an analytic expression for the temperature dependent anisotropy. The reduced magnetization in the film surface at finite temperatures plays a crucial role for this transition as with increasing temperature the influence of the uniaxial anisotropies is reduced at the surface and is enhanced inside the film.
@article{arxiv.cond-mat/9701043,
title = {Reorientation transition of ultrathin ferromagnetic films},
author = {A. Hucht and K. D. Usadel},
journal= {arXiv preprint arXiv:cond-mat/9701043},
year = {2009}
}