Effect of roughness on perpendicular magnetic anisotropy in (Co90Fe10/Pt)n superlattices

Superlattice [Co90Fe10(0.21)/Pt(0.23)](n) (unit in nm) with the repeat cycles n ranging from 3 to 30 were studied. Both effective anisotropy (K-eff) and PMA constant (K-U) reached a maximum at n=8. When the 3 nm Pt underlayer was deposited at low energy condition, the K-eff and K-U of (CoFe/Pt)(8) are 4.0 and 6.1 Merg/cc, respectively. On the other hand, the K-eff and K-U increased to 6.8 and 9.7 Merg/cc, respectively, when the Pt underlayer deposited at high energy condition. As the n increases, the surface roughness monotonously increases and d(111) inside the superlattice layers increase and relax from bottom to top part. The interface roughness and relaxation in superlattice reduce the PMA considerably. (C) 2016 Author(s).