Effect of Cu, Cu/Ru, or Ru/Cu seed-layer on perpendicular magnetic anisotropy of Co80Pt20 films

The magnetic anisotropy of Co80Pt20 films deposited directly on glass substrates (without any seed layer) at room temperature tends to be inclined. The degree of perpendicular magnetic anisotropy can be slightly increased by introducing a Cu layer or a Cu/Ru (Cu on Ru) bilayer under the Co80Pt20 film. However, when Co80Pt20 films are deposited onto a Ru/Cu (Ru on Cu) bilayer, the magnetic anisotropy of the films becomes perpendicular. Moreover, from this study, we found that an fcc Cu (1 1 1) under-layer can promote the hcp Ru (0 0 0 2) seed layer, which can, in turn, induce a good (0 0 0 2) texture in the hcp Co80Pt20 magnetic layer. As a result, Co80Pt20/Ru/Cu/glass films display excellent (or improved) perpendicular magnetic anisotropy. In conclusion, our results showed that columnar Co-rich Co-Pt nano-grains with perpendicular coercivity of 4580 Oe and perpendicular squareness of 0.77 can be achieved by depositing Co80Pt20 (50 nm) film onto a Ru (30 nm)/Cu (100 nm) bilayer, with a glass substrate, at room temperature.