A magnetic recording layer having polycrystalline chemical ordered (COX).sub.3Pt or (COX).sub.3PtY alloys. The additive X comprises Sc, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Hf, Ta, W, Re, Os, B, or C, or any combination thereof. The additive Y comprises B, MgO, Al.sub.2O.sub.3, SiO.sub.2, P, CaO, CoO, B.sub.2O.sub.3, ZnO, NbO, Mo.sub.2O.sub.3, Co.sub.2O.sub.3, C, Cr, P, TiO.sub.2, Cr.sub.2O.sub.3, MnO, ZrO.sub.2, or BaO. The ratio of (CoX) to Pt is 2.33 to 4.00, plus or minus 5%. The additive Y may range from approximately 0 to 20% of the entire composition. The magnetic layer may be a constituent layer in a hard disc drive magnetic recording medium.