Reducing the writing field of L1-FePt by graded order parameter Available to Purchase

The dependence of the magnetic properties of epitaxial Fe₅₀Pt₅₀ films on order parameter (S) was investigated. It was demonstrated that the magnetic anisotropy could be tuned by controlling S which can be controlled by the growth temperature. Based on this result, two kinds of multilayered structures, each with a 13 nm fully ordered Fe₅₀Pt₅₀ layer as the bottom layer, were built: (1) 4-layered structure with S decreasing layer by layer from bottom to top; (2) graded structure with S changing more continuously along the thickness. The magnetic properties of the films were characterized using vibrating sample magnetometry. It was found that both structures have their easy axis perpendicular to the film; the anisotropy fields of the 4-layered film and the graded film are 53 kOe and 37 kOe, respectively. These values are much lower than that of the fully ordered uniform Fe₅₀Pt₅₀ film (about 73 kOe). The results suggest that it may be possible to reduce the writing field of Fe₅₀Pt₅₀ by gradually changing the order parameter.