The structural transition from epitaxial Fe/Pt multilayers to an ordered FePt film using low energy ion beam sputtering deposition with no buffer layer

• The Fe/Pt films using ion sputtering deposition with no buffer layer is epitaxial.
• Multilayer structure was totally disappeared at temperatures higher than 600 °C.
• Order parameter reach 0.95 after annealing at 650 °C.
• Interfacial epitaxial FePt alloy already formed at 100 °C.

An epitaxial L10 FePt thin film grown from an [Fe(10 Å)/Pt(10 Å)]15 multilayer with the orientation of (001) was prepared by an ion beam sputtering deposition method without buffer layer. From the measurement data of X-ray diffraction and X-ray reflectivity, the multilayer structure was totally disappeared and a uniform FePt alloy thin film was formed at temperatures higher than 600 °C. For the as-deposited thin film grown at 100 °C, the multilayer already possesses an epitaxial structure. The epitaxial relation is FePt(001)[100]//MgO(001)[100] and this epitaxial relation persists after sequential high temperature annealing. An epitaxial L10 ordered FePt(001) film with order parameter of 0.95 was obtained when the annealing temperature reached 650 °C. The ordered FePt(001) thin film has a perpendicular magnetic anisotropy with a squareness of 0.95 ± 0.03 on the magnetic hysteresis loop. This experiment demonstrates that the low energy ion beam sputtering deposition will preserve the epitaxial relation with no buffer layer between multilayer and substrate.