Magnetic Anisotropy of Co-M-Pt ( ${\rm M}={\rm Cr}$, Mo, Ru, W, Re) Perpendicular Films Deposited on Various Seed Layer Materials

The first and second order uniaxial magnetic anisotropy, K
_u1
and Ku2, and the saturation magnetization, M
_s
, of (Co
_100-X
M
_X
)
_100-Y
Pt
_Y
perpendicular thin films were examined, in order to improve the magnetic properties of CoCrPt-SiO
₂
media by replacing Cr with M. Fourteen kinds of M elements were examined, but we mainly focus on films with M=Cr, Mo, Ru, W and Re in this paper, since the other elements significantly reduced Ku1,Ku2 or the K
_u
/M
_s
ratio. The use of the M elements, instead of Cr, did not result in any significant increase in the values of K
_u1
, K
_u2
, and the Ku/M
_s
ratio. On the other hand, K
_u1
and K
_u2
of CoPt binary films had a greater dependence on the seed layer materials used (Ru, Pd, Re, Pt, Au, Ir and Cu). The c/a ratio of the hcp-CoPt lattice varied significantly with the seed layer materials used probably due to the epitaxial growth of CoPt. K
_u1
decreased and K
_u2
increased as the c/a ratio increased. The use of specific seed layer materials was more effective at controlling the magnetic anisotropy of CoPt based perpendicular thin films, rather than the addition of M element to the CoPt