The effect of TaOx capping layer on microstructures and magnetic properties of FePt thin films via annealing was studied. The structural ordering of FePt from face-centered cubic to face-centered tetragonal phases depends strongly on the oxygen contents in the capping TaOx layer. The role of the TaOx layer is used to separate the FePt grains, as revealed by TEM. The annealed FePt/TaOx (15%O2/Ar) exhibited the largest out-of-plane coercivity (Hc 4.2 kOe) amongst all samples, compared to that (∼2.4 kOe) in the reference FePt layer. At low oxygen content in FePt/TaOx bilayers, the Ta atoms may act as defects to obstruct the FePt ordering whereas at high oxygen contents, the excess oxygen atoms diffuse into the FePt layer and react with Fe to form iron oxides which give rise to the low coercivities, as characterized by the XPS depth profile and binding energy analysis.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering
- ion-beam bombardment
- magnetic properties