Magnetic properties of L10 FePt and FePt:Ag nanocluster films

A sputtering gas-aggregation technique has been used to prepare FePt and FePt:Ag nanocluster films. The cluster size was controlled in a range from 3 to 6 nm. FePt cluster films were directly deposited onto Si substrate; FePt:Ag cluster films were fabricated by depositing a FePt cluster layer between a Ag underlayer and overlayer. Nanostructure and magnetic properties of the samples were characterized by x-ray diffraction, transmission electron microscopy, and magnetometry. The high magnetic anisotropy L1(0) fct phase was realized in the films annealed at a temperature of 550 degreesC and above. The orientation of clusters is random. The coercivity increases with an increase of annealing temperature; high in-plane and out-of-plane coercivities, exceeding 10 kOe, were achieved in both FePt and FePt:Ag cluster films after annealing. For FePt:Ag films, the coercivity increases with Ag underlayer thickness, t(Ag), and reaches about 17 kOe at room temperature for t(Ag)=5 nm after annealing at 650 degreesC for 10 min. The high coercivity is closely correlated with the degree of L1(0) ordering and nanostructure of the films. (C) 2003 American Institute of Physics.