Applied Surface Science, Vol.252, No.24, 8688-8694, 2006
Characterization of Cu additive FePt-C granular films
FePt-C granular films doped with different Cu atomic fractions (x(Cu)) were fabricated using facing-target sputtering at room temperature and subsequently annealed at 650 degrees C. Structural analyses reveal that the as-deposited films are in amorphous state. Appropriate Cu addition (x(Cu) = 14) can improve the ordering of L1(0) FePt phase, and excessive Cu doping destroys the formation of ordered L10 phase with the appearance of Fe3C and CuPt phases. Besides, preferential graphitization of amorphous carbon (a-C) occurs near large metal particles upon annealing. Annealing turns the as-deposited superparamagnetic films into ferromagnetic associated with coercivity peaks at x(Cu) = 14, drops from similar to 11.2 kOe at 5 K to similar to 7.2 kOe at 300 K in a 50 kOe field. (c) 2005 Elsevier B.V. All rights reserved.