Studies of Exchange Coupling in FeCo/L10-FePt Bilayer Thin Films

FeCo/FePt bilayer thin films were synthesized by RF/dc sputtering on Si <100> substrate, and characterized for structural and magnetic properties. Synchrotron X-Ray diffraction revealed L1(0) phase of FePt and amorphous FeCo after annealing. An attempt was made to increase the strength of interfacial exchange coupling in FeCo/FePt bilayer thin films by varying the thickness of the soft layer. The in-depth analysis of reversal process at the interface was carried out using recoil curves. A giant energy product 47 MGOe was obtained for the FeCo(6 nm)/FePt(27 nm) bilayer thin film. The system was modeled by using micromagnetic simulations to visualize the magnetization reversal at the interface. Quantitative estimation of exchange energy was made and its variation with the reverse field was studied in order to understand the coupling between the hard and soft layers.