A Controllability Investigation of Magnetic Properties for FePt Alloy Nanocomposite Thin Films

An appropriate writing field is very important for magnetic storage application of L1₀ FePt nanocomposite thin films. However, the applications of pure L1₀ FePt are limited due to its large coercivity. In this paper, the ratios of L1₀ and non-L1₀ phase FePt alloy nanoparticles in FePt/MgO (100) nanocomposite thin films were successfully tuned by pulsed laser deposition method. By adjusting the pulsed laser energy density from 3 to 7 J/cm², the ordering parameter initially increased, and then decreased. The highest ordering parameter of 0.9 was obtained at the pulsed laser energy density of 5 J/cm². At this maximum value, the sample had the least amount of the soft magnetic phase of almost 0%, as analyzed by a magnetic susceptibility study. The saturation magnetization decreased with the increase in the content of soft magnetic phase. Therefore, the magnetic properties of FePt nanocomposite thin films can be controlled, which would be beneficial for the magnetic applications of these thin films.