L10 FePt Nanoparticles Processing with Applied Magnetic Field

Due to the strong magnetic anisotropy energy, the L1₀ FePt nanocrystals are considered as one of promising candidates for magnetic recording media with ultrahigh densities. The surfaces of Si and SiO₂ wafers have been covered by FePt nanoparticles (NPs) and heated at 600 °C for 1 h to form the L1₀ phase. Bonding of NPs with the SiO₂ surface in the presence of magnetic field during annealing process controls the L1₀ FePt NPs size and their uniform surface distribution. In the presence of perpendicular magnetic field to the surface, the size of NPs obtains up to 30 nm with coercivity of 5.8 kOe and in parallel magnetic field, the NPs size reaches to 45 nm with coercivity of 2.9 kOe. These results and the easy axis ordering of samples have been determined by energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer analyses.