Development of FePt-Si-N nanocomposite thin films for magnetic recording

Nanocomposite FePt-Si-N thin films consisting of magnetic L10 FePt nanograins and non-magnetic Si-N matrix for high density recording medium are developed in this work. The (FexPt100-x)100-ySiy-N films (x = 50-65 and y = 0-10) were fabricated on Si (100) substrates by dc reactive magnetron sputtering followed by vacuum annealing. The maximum value of coercivity around 15.3 kOe was obtained in the film with atom ratio Fe:Pt = 55:45. To achieve a high coercivity, the concentrations of Si and N also have to be properly controlled. Doping Si-N improves the coercivity of FePt film through weakening the exchange coupling interaction. Si and N also play an important role in reducing average grain size of the magnetic particles and smoothing the surface of the films. Transmission electron microscopy demonstrated the nanogranular structure consisting of FePt nanoparticles embedded in the amorphous Si-N matrix.