Coercivity exceeding 100 kOe in epitaxially grown FePt sputtered films

Microstructure and magnetization processes of highly ordered FePt (001) films with large perpendicular magnetic anisotropy have been studied. The film morphology was controlled from assemblies of single-domain nanoparticles to those of multidomain islands by varying the nominal thickness (t(N)) of the FePt films sputter-deposited on a heated MgO (001) substrate. The change in the magnetization process from magnetization rotation to domain wall displacement is clearly demonstrated by the initial magnetization curves. Huge coercivities as high as 70 and 105 kOe have been achieved in the film with single-domain particles at room temperature and 4.5 K, respectively. (C) American Institute of Physics.