Magnetic Properties and Microstructure of FePt Films With MgTiON Intermediate Layer

The magnetic properties and microstructure of FePt films grown on MgTiON intermediate layer were studied. The MgTiON layer was deposited by sputtered (MgTi)ON target at 395 °C. The MgTiON (002) texture was formed on CrRu (002)/glass. Furthermore, the 10 nm thick FePt film was deposited on MgTiON at 450 °C. The FePt shows perpendicular magnetization with out-of-plane coercivity of 3.62 kOe. Smaller FePt out-of-plane coercivity may come from lower ordering degree and continuous layer structure, which provides easy domain wall motion. To promote the ordering of FePt film, thinner MoC layer with thickness of 1 to 3 nm was capped on MgTiON (30 nm) layer during sputtering process. The FePt films with thickness from 4 to 10 nm show perpendicular magnetic anisotropy and the out-of-plane coercivities were increased to 11.9-15.3 kOe. The significant change of FePt out-of-plane coercivity was explained by ordering degree and microstructure. The island growth was dominated when FePt film prepared on thinner MoC interface and the excess carbon from MoC layer was diffused up to promote the ordering of FePt during sputtering. As a result, higher FePt out-of-plane coercivity on MoC/MgTiON intermediate layer was due to higher ordering degree and domain wall pinning effect in separated FePt islands.