Improvement of hard magnetic properties in microfabricated L10-FePt dot arrays upon post-annealing

Epitaxial L1₀-FePt [001] dot arrays were fabricated through the use of a microfabrication process. The lateral size of square dots was changed in the range of 0.2 to 5 μm. The coercivity (H_c) increased after patterning a continuous film to dot arrays. Furthermore, H_c was drastically enhanced by post-annealing, and H_c exceeding 20 kOe was achieved for the dots with 0.2×0.2 μm² annealed at 600°C, in contrast to the continuous film showing low H_cof 1kOe. The enhancement of H_c for dot arrays upon annealing was attributed to the decrease of structure defects caused by the damage due to the microfabrication, which provide the nucleation sites where reversed domains are generated at a low field.