Reorientation transition of ultrathin ferromagnetic films

TL;DR

This paper explains the temperature-driven reorientation transition in ultrathin ferromagnetic films using a microscopic model, highlighting the role of surface magnetization reduction and anisotropy changes.

Contribution

It provides an analytic expression for temperature-dependent anisotropy based on mean field and perturbation theories, explaining experimental observations.

Findings

Reorientation transition explained microscopically

Surface magnetization reduction influences anisotropy

Analytic expression for anisotropy as a function of temperature

Abstract

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.