Abstract
FeXPt1-X(x=46-58) and FePt-MgO thin films with thickness 40 nm were deposited by dc- and rf-magnetron sputtering onto Corning7059 glass substrate at room temperature with further post-annealing in order to investigate the effect of MgO addition on the magnetic and structural properties of FePt alloy films. Co-sputtering, reactive sputtering and post oxygenation during annealing were used to prepare Fe-Pt-Mg-O films, respectively.Optimum magnetic properties of the films were obtained at composition Fe57Pt43. The saturation magnetization (Ms) of as-deposited Fe57Pt43 films is 1028 emu/cc. After annealing at 500oC for 30 minutes, the FePt film undergoes an ordering transition from the disordered fcc to ordered fct structure. Its coercivity (Hc) is about 10.3 kOe and Ms around 741emu/cc. Magnetic properties were affected by adding MgO into FePt films. (1) In reactive sputtering process, the oxygen/argon ratio (0.2-1%) was varied to get FePt-Mg-O film. The best magnetic properties were from 0.2% oxygen with a maximum Hc 12.3 kOe. (2) In co-sputtering process, RF-power was controlled to get (FePt)100-x-(MgO)x films with different MgO volume ratios. The optimal Hc is 4 kOe and Ms 772 emu/cc, and the squareness ratio (S) is also improved from 0.79 to 0.83. (3) The FePtMg alloy films were deposited by reactive sputtering process. The ordering temperature for γ2-FePt formation can be significantly lowered down to 300oC, with an Hc 3.7 kOe and Ms 1100 emu/cc.