High Coercivity FePtSiN Films With L10-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 degrees 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 degrees 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.