High Coercivity FePtSiN Films With L1 $_{0}$ –FePt Nanoparticles Embedded in a Si-Rich Matrix

FePtSiN films consisting of FePt nanoparticles embedded in Si-rich matrix were fabricated on silicon substrates by direct current (dc) reactive magnetron sputtering followed by vacuum annealing. The effects of Si-N additions and annealing temperature on the structure and magnetic properties were investigated. The as-deposited films had face-centered cubic (fcc) structure, which transforms into the face-centered tetragonal (fct) structure after thermal annealing at 600°C. The grain size of FePt increased with the annealing temperature but decreased with increasing Si-N content. Increasing Si content led to the formation of Si-N-rich amorphous phase distributed between the FePt nanograins, which reduced the lattice distortion and increased the coercivity. The fct-FePt films annealed at 700°C exhibited very high coercivity, up to 13.6 kOe at room temperature and about 17.5 kOe at 100 K. These FePtSiN films have shown promise for high-density magnetic recording medium.