Magnetic properties and microstructure of Fe/FePt films with perpendicular magnetization

The soft/hard Fe/FePt bilayer with perpendicular magnetization has been prepared successfully on glass substrate. The (001) oriented L1₀ FePt film with fix thickness 10 nm was deposited on glass and subsequently annealing by rapid thermal process (RTP) at 800°C for 5 minutes and a Fe layer was deposited at room temperature with thickness of 2 nm to 10 nm. The control of Fe layer thickness allowed modifying the hysteresis loops from rigid magnet to exchange-spring magnet due to the nanoscale soft/hard interface coupling. When the Fe layer thickness increased to 3 nm, the out-of-plane coercivity is reduced to 5.88 kOe but the remanence ratio (0.98) is high. The Fe (3 nm)/FePt bilayer shows perpendicular magnetization with linear in-plane hysteresis loop. The remanence ratio is reduced to 0.86 when the Fe layer thickness increased up to 6 nm. When the Fe layer increased up to 10 nm, the hysteresis loop shows exchange spring-like behavior. The out-of-plane coercivity is still 4 kOe but the remanence ratio is 0.19. The films with perpendicular coercivity were moderated successfully by the soft magnetic layer with different thickness.