Perpendicular magnetic anisotropy in nanostructured pseudomorphic Fe(110) films on W(110)

Pseudomorphic Fe(110) films, deposited on W(110) at room temperature. with a mean thickness of 1.5 monolayers. are composed of double layer islands with a diameter of the order of 10 nm on a monolayer sea. The double layer islands are ferromagnetic (superparamagnetic) below 500 K, the monolayer sea becomes ferromagnetic below 222 K. Magnetic anisotropy is uniaxial in both components. The easy axis is perpendicular to the film plane in the double layer islands anti within the film plane (along [110]) in the monolayer sea. The perpendicular anisotropy in the double laver islands apparently is caused by the pseudomorphic strain, The lateral scale for the anisotropy switching roughly coincides with the exchange lengths in both media. The strength of the exchange interaction between double layer islands rapidly increases when the monolayer sea becomes ferromagnetic.