High perpendicular hard magnetic properties of nanocomposite Co-rich Co–Pt/Pt double-layered films by epitaxial deposition without capped layer

The HRTEM cross-sectional lattice image shows that a well epitaxial growth of hcp Co-rich Co–Pt (002) on Pt (111) underlayer leads to good perpendicular magnetic anisotropy of Co-rich Co–Pt film. It is found that both the perpendicular coercivity (Hc⊥) and perpendicular squareness (S⊥) of Co-rich Co–Pt films without Pt capped layer are larger than that of Co-rich Co–Pt films with Pt capped layer. The cross-sectional TEM-EDS and AES analysis confirm that the oxygen atoms will diffuse from film surface into the Co-rich Co–Pt film without adding Pt capped layer, and it react with cobalt atoms to form CoO, which is detected by XPS analysis. The increase in perpendicular hard magnetic properties of Co-rich Co–Pt film without Pt capped layer is mainly due to form CoO in the Co-rich Co–Pt film.