Magnetic anisotropy of Fe∕Pt(001) and Pt∕Fe∕Pt(001) using a first-principles approach

We investigated the magnetic anisotropy of an iron layer on a Pt(001) surface and some related systems by employing the local spin density approximation in a theoretical ab initio approach. We found that the surface system Pt∕Fe∕Pt(001) showed a perpendicular magnetic anisotropy and its anisotropy energy per iron atom amounted to a value which is 2 times larger than the value of bulk FePt. The surface relaxation much enhances the anisotropy energies, related to a large attractive force between the iron and platinum layers. A remarkable cap effect—that the covering platinum layer changes anisotropy energy—was also found to exist. We investigated the microscopic origin of the perpendicular anisotropy in relation to the local densities of states of the Fe atom. These quantities were discussed as a fingerprint of magnetic anisotropy in comparison with the results of the Fe chain at the step edge on a vicinal surface Pt(664). The atomic orbital magnetic moments were enhanced at the respective surface atoms.