Formation of octahedral FePt nanoparticles by alternate deposition of FePt and MgO

Two-dimensional assemblies of octahedral-shaped FePt nanoparticles embedded in a MgO matrix were formed by alternate deposition of FePt and MgO layers on MgO (001) single-crystal substrates with a thermal cycling process. Highly ordered L1(0) structure with the [001] orientation perpendicular to the plane and large coercivity of more than 60 kOe were obtained. Cross-sectional transmission electron microscopy observation revealed that the equilibrium crystal shape of L1(0) ordered FePt particles was octahedral structure due to the anisotropy of the surface energy. The {111} plane shows the minimum surface energy in the L1(0) structure, which is similar to the case of face-centered-cubic structure.