Co50-xMxPt50 (M - Cu or Ru) films were magnetron sputtered on textured Pt(111) underlayer on glass substrate at 350 degrees C. The results show that perpendicular magnetic anisotropy of superlattice Li1 phase can be maintained well with doping Cu element into CoPt film. Out-of-plane coercivity (H-c perpendicular to) was also increased with the increase of Cu content. However, disordered A1(111) structure and lower H-c perpendicular to were obtained with the addition of Ru element in CoPt film. The magnetic force microscopy images indicated that doping Cu diminished the domain size. Oppositely, doping Ru made the domain reversed incompletely. Surface morphology of Co50-xMxPt50 thin film was much smoother than that of Co50-xMxPt50 thin film, indicative of maintenance of the epitaxial growth of Ll(1) 1(111) from flat Pt(111) underlayer. The transmission electron microscopy (TEM) images show that the Cu element could be incorporated in Li1 CoPt grains; however, the RuPt alloy was segregated at CoPt grain boundary. The cross section TEM pictures showed that the columnar structures starling from Pt(Hi) underlayer and extending into magnetic CoCuPt(111) layer confirmed that epitaxy existed at Co50-xMxPt50 interface. Our research demonstrates that replacing Co with Cu 23-26 at.% effectively increases the perpendicular magnetic properties of Ll(1) CoPt phase, which largely increase the potential of Ll(1) films for the application of perpendicular magnetic media and advance spintronic device. (C) 2014 Elsevier BY. All rights reserved.