Structure and magnetic properties of FePt nanograins embedded in amorphous carbon films

Amorphous carbon films with nanograin inclusions of FePt alloy were manufactured by a DC magnetron co-sputtering technique. All films show superparamagnetism. After the post-deposition annealing, the blocking temperature and, thus, the coercive field are largely increased. The coercivity increases from ∼1.7 kOe of the as-deposited films to ∼5.6 kOe of the films annealed at 400 deg. C for 1 h. We discuss the effect of annealing on the structure and the increase of coercivity