Composite nanogranular films of FePt-MgO with (001) orientation onto glass substrates

For perpendicular magnetic recording, a design of using MgO as a seed layer and an intermediate layer is introduced. By annealing the multilayer film with a stack structure of $\mathrm{MgO}\mathrm{/[}\mathrm{FePt/MgO}{]}_3$ at $\text{600\hspace{0.05em}°}\mathrm{C}$ for 1 min, nanograins of FePt with a high perpendicular magnetic anisotropy are obtained on a glass substrate. This high magnetic anisotropy results from the (001) texture of ${\text{L1}}_0$ phase developed along the film normal. A thin MgO layer ranging 1.0 to 3.0 nm in thickness plays an important role in developing the (001) texture of ${\text{L1}}_0$ FePt and magnetically decoupling the FePt particles. Varying a layer thickness of the FePt layer enables to control the crystalline structure and the magnetic properties, resulting in the films with a controllable FePt grain size as small as several nanometers, a high remanence squareness, and a high coercivity.