Annealing temperature dependence of magnetic properties in FeCo ordered alloy thin films fabricated using the nitrogen surfactant effect

L10-FeCo has attracted attention as a new, rare-metal-free magnetic material due to its large uniaxial magnetic anisotropy. However, the low stability of the L10 phase hampers its practical application. We here intend to prepare FeCo alloy thin films by utilizing the nitrogen surfactant effect. The enhancement of the out-of-plane magnetization of this thin film was observed by stacking cobalt single atomic layer on bilayer iron nitride and subsequent annealing at 470 K. This study provides an insight into the relationship between structural changes and magnetic properties of the FeCo interface on the atomic scale, and paves the way for the development of rare metal-free magnetic materials.