Perpendicular thin films of carbon-doped FePt for ultrahigh-density magnetic recording media

The microstructural and magnetic properties of the carbon-doped equiatomic (Fe₅₀Pt₅₀)_1-xC_x thin films, prepared by dc magnetron cosputtering on MgO (100) substrates held at 400°C, were investigated. Particles consisting of the highly anisotropic tetragonal L1₀ FePt phase and embedded in a C matrix were obtained. By controlling the added C content, the samples with average grain size of 5 nm were obtained with perpendicular coercivity of about 5 kOe. The remanence ratio kept high values of about 1 when x≤25 vol%, and it decreased abruptly as x>25 vol%. The room temperature magnetic measurements suggest that the perpendicular magnetic anisotropy exists for these films with C concentration up to 25 vol%. The obtained results suggest that this system might be applicable to ultrahigh-density magnetic recording media.