Magnetic anisotropy of L1₁-type (Co_1-XM _X)₅₀Pt₅₀ (M:Ni, Fe, Cr, Mn) and Co ₅₀(Pt_1-XPd_X)₅₀ ordered alloy perpendicular films

We substituted 3d transition elements M (M=Ni, Fe, Cr, and Mn) for some of the Co, or Pd for some of the Pt, in L1₁-type Co₅₀Pt ₅₀ ordered alloy perpendicular films, and studied magnetic and structural properties. Films were fabricated at a substrate temperature of 360^oC using ultra-high vacuum (UHV) sputter film deposition. The order parameter S was almost a constant of about 0.5 when Ni was substituted for some of the Co. The uniaxial magnetic anisotropy K_u and the saturation magnetization, M_s, decreased as the Ni content increased, however, K_u maintained a relatively large value of 1.8x10⁷ erg/cm³ (M_s=570 emu/cm³) even for a Co ₂₀Ni₃₀Pt₅₀ composition. In the substitutions of Fe for some of the Co, or Pd for some of the Pt, no significant variation in M_s was observed, however, the rate of decrease of K_u on increasing the Fe or Pd content was larger than when Ni was substituted. The substitution of Cr or Mn for some Co resulted in significant reductions in S, M_s and K_u. Experimental results showed the potential of Co-Ni-Pt ordered films for use in data storage applications, due to their very high K_u potential, relatively low M_s, the relatively low fabrication temperature, and good controllability of the grain orientation.