Thickness reduction in CoPtCr-SiO2 perpendicular recording media to improve media performance

T. Shimatsu, T. Oikawa, Y. Inaba, Hideo Sato, I. Watanabe, H. Aoi, Hiroaki Muraoka, Y. Nakamura

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Magnetic properties and recording performance of thin CoPtCr-SiO 2 media were examined in relation to thermal stability. Magnetic anisotropy Ku of {(Co90Cr10) 80Pt20}89-(SiO2)11 media maintains a constant value of around 5.5 × 106 erg/cm 3, even at film thickness of 4 nm. This Ku value corresponds to the anisotropy energy of the grains Ku9 calculated by taking account of the volume fraction of about 8 × 10 6 erg/cm3, indicating a high potential to resist thermal agitation. The high Ku derives a high remanence corcivity H r of ∼ 4 kOe, even at film thickness of 8 nm, resulting in a loop squareness of nearly 1. The ratio of magnetic anisotropy energy to thermal energy KuVactkT maintained a value of more than 70, even at this thickness. The media noise at low recording density increases with decreasing film thickness below 8 nm, probably due to the thermal agitation. The recording resolution D50 showed a broad maximum of ∼ 420 kFCI at around this thickness. The reduction in Sim thickness improves recording resolution; however, it is likely that the large thermal agitation in the thin-film region degrades the recording resolution, resulting in an optimum thickness to show the highest recording resolution.

Original languageEnglish
Pages (from-to)2461-2463
Number of pages3
JournalIEEE Transactions on Magnetics
Issue number4 II
Publication statusPublished - 2004 Jul


  • CoPtCr-SiO
  • Coercivity
  • Magnetic anisotropy
  • Media noise
  • Perpendicular recording media
  • SiO content
  • Thermal agitation of magnetization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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