Substantial reduction in coercivity of perpendicular CoPt/FePt graded films with near-atomic flatness on glass substrates

• Published in: Journal of alloys and compounds 2015-05, Vol.631, p.15-20
• Main Authors: Liu, S.H., Hsiao, S.N., Chen, S.K., Lee, H.Y.
• Format: Article
• Language: English
• Subjects: FePt thin films; Graded media; Near-atomic flatness; Reduced coercivity
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2015.01.076

•Perpendicular graded films comprising soft Co66Pt34 layer and hard L10-FePt layer deposited on glass substrates.•Microstructure observations reveal the epitaxial growth of the CoPt layer on (001) FePt film.•Substantially reduced coercivity (Hc) and the near-atomic flatness of surface morphology of the graded films are obtained.•Well exchange-coupled graded films are characterized at a soft layer thickness within 20nm. Perpendicular graded films comprising soft Co66Pt34 layer and hard L10-FePt layer deposited on glass substrates were investigated. Microstructure observations reveal the unidirectional growth of the CoPt layer on (001) FePt film. By controlling the deposition temperature of soft layer and interlayer diffusion, the substantially reduced coercivity (Hc) and the near-atomic flatness of surface morphology are simultaneously obtained. In comparison to the single-layered FePt, Hc of the optimal graded film is significantly reduced by a factor of 4, while the surface roughness of the graded film lower than 0.3nm is obtained. Depth-resolved techniques prove that the gradation of L10 ordering could lead to the reduction of Hc and switching field distribution due to the enhancement of interlayer exchange coupling. Well exchange-coupled graded films are characterized at a soft layer thickness within 20nm.