Improvement of Magnetic Properties in Microfabricated FePt and Fe Nano-Composites Upon Post-Annealing

In order to evaluate the magnetic properties of cylindrical nanocomposite magnets, microfabrication, electron beam lithography, and Ar ion etching were used to prepare hard, ring-shaped, L10 ordered FePt structures embedded with body-centered cubic Fe cores. L1e FePt has high uniaxial magnetic anisotropy, moderate saturation magnetization, and excellent corrosion resistance. Magnetic properties were measured by magneto-optic Kerr effect, magnetometry, and magnetic force microscopy before and after annealing. Coercivity of the FePt/Fe structures with inner diameter 1.0 μm increased from 4.5 kOe to 8.4 kOe with post-annealing at 500 °C for 1 hour.