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 (Keff) and PMA constant (KU)
reached a maximum at n=8. When the 3 nm Pt underlayer was deposited at low
energy condition, the Keff and KU of (CoFe/Pt)8 are 4.0 and 6.1 Merg/cc, respectively.
On the other hand, the Keff and KU 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 d111 inside the superlattice layers
increase and relax from bottom to top part. The interface roughness and relaxation
in superlattice reduce the PMA considerably.