Microstructure and magnetic properties of FePt-SiO2 granular films with Ag addition

Perpendicularly anisotropic L1(0)-ordered FePt-SiO2 granular films with an average grain size of 15 nm and a relatively narrow size distribution were prepared by cosputtering Fe, Pt, and SiO2 on MgO (001) substrates at 700 degrees C. By reducing the substrate temperature to 500 degrees C, the average grain size was further refined to 6.2 nm with a standard deviation of 1.7 nm; however, the FePt particles remained as an A1 disordered phase. Alloying Ag to the FePt particles and increasing the Ar gas pressure in the sputtering chamber were found to be both beneficial for enhancing the L1(0) ordering while keeping the fine granular structure. (C) 2008 American Institute of Physics.