Epitaxial Growth of L1 $_{0}$ –FePt Granular Thin Films on TiC/RuAl Underlayers

Highly ordered L1₀ FePt-oxide thin films with perpendicular texture and small grains were fabricated on a TiC underlayer along with a RuAl small grain size layer and a MgO seedlayer. The epitaxial growth from the MgO seedlayer to the TiCRuAl grain size defining underlayer to FePt magnetic layer was studied. Perpendicular texture can be further improved by adjusting the thickness of each layer to optimize the in-plane stain. From our microstructure study, TiC/RuAl grain size defining layer was found effective in reducing the volume fraction of oxide in the film and the center-to-center grain size of FePt grains. With a thin Ag sacrificial layer inserted between TiC and FePt magnetic layer, a smaller grain size can be achieved, the ordering temperature was lowered, and the (001) texture of FePt was enhanced.