Effect of continuous layer in CGC perpendicular recording media

Y. Sonobe, K. K. Tham*, T. Umezawa, C. Takasu, J. A. Dumaya, P. Y. Leo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


The effect of continuous layer on CoCrPt-SiO2 granular layer is studied in coupled granular continuous (CGC) perpendicular recording media. In the cross-section transmission electron microscope (TEM) observation, magnetic grain in the granular layer shows columnar structure, while Co/Pd multilayer shows continuous layer. The plane-view TEM image of the granular layer shows well-isolated grain structure with average grain size of around 6 nm, and grain-to-grain separation width of around 2 nm. Therefore, the interactions among the grains are negligible (J∼0). By depositing a continuous layer on a CoCrPt-SiO2 granular layer, the grains in the granular layer are magnetically coupled through capping layer that leads to the suppression of magnetic anisotropy dispersion. This CGC structure reduces the coercivity dispersion ( Δ Hc / Hc) from 0.26 to 0.15 and saturation field (Hs) from 10.4 to 6.7 kOe. The reduction of Hs and Δ Hc / Hc improves the OW by 21.3 dB. The small Δ Hc / Hc also maintains SNR of CGC media with strong magnetic exchange coupling. Furthermore, the coupling of grains through continuous layer enlarges the magnetic nucleation field (Hn) from 0.4 to -1.7 kOe. Consequently, CGC media shows better thermal stability compared to non-CGC media.

Original languageEnglish
Pages (from-to)292-295
Number of pages4
JournalJournal of Magnetism and Magnetic Materials
Issue number2 SPEC. ISS.
Publication statusPublished - 2006 Aug
Externally publishedYes


  • Cross-section and plane-view TEM observation
  • H
  • H
  • Thermal stability
  • Δ H / H

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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