Executive Summary : | Recently thin films of metallic multilayers and rare-earth transition metal alloys have drawn considerable interest to the scientific community for their potential application in magnetic storage media. For decades, L10-ordered FePt thin films have drawn the attention of researchers remarkably because of their potential applications in high-density heat-assisted magnetic recording media due to their large magnetic anisotropy energy density. Under normal deposition conditions, FePt films are usually grown in a disordered FCC structure which has low magnetic anisotropy energy density with an easy axis along the film plane and possesses soft magnetic properties. However, for application in perpendicular magnetic recording technology, the FePt film must be fully transformed from disordered FCC to L10 phase. It was observed that upon annealing of the films, the FCC changes to L10 ordered with easy axis in direction perpendicular to film plane. Several investigations on FePt alloy films, FePt/Ag bilayer films, and FePtAg ternary alloy thin films have been reported due to their potential application to replace present conventional CoCrPt-based storage media. For application in high areal density (~ Tb/in2) recording media, FePt-based films should have high magnetocrystalline anisotropy energy, high saturation magnetization (MS) and beyond room temperature Curie temperature. The material properties like magnetic anisotropy, curie temperature, structural ordering temperature, and crystallographic orientation of FePt alloy film can be manipulated by adding third elements such as Au, Ag, Cr, Mn, Cu, Ni, etc. It is observed from the literature review that a number of studies have been carried out on FePt-based thin films as well as doped with third elements such as transition elements, rare earth elements, C, N, etc. to promote the perpendicular magnetic anisotropy with enhanced magnetic parameters. However, limited studies were done on Co-doped FePt thin films and thus, the influence of Co doping on structural and magnetic properties is not well understood. The annealing of these films at elevated temperatures above 400℃ is expected to transform the FCC phase to L10 FCT phase, whose magnetism is yet to be understood. The magnetic behavior of these materials with varying thicknesses of the films and the influence of insertion of magnetic/nonmagnetic underlayer to tune the perpendicular magnetic anisotropy with an easy axis along c-axis need to be understood. Additionally, we will look at the influence of surface roughness on the magnetic properties of these films. All the above-mentioned studies are believed to provide a new understanding of the magnetic behavior of Co-doped FePt thin films. |