Coupled granular/continuous medium for thermally stable perpendicular magnetic recording

Y. Sonobe*, D. Weller, Y. Ikeda, K. Takano, M. E. Schabes, G. Zeltzer, H. Do, B. K. Yen, M. E. Best

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

78 Citations (Scopus)


We studied coupled granular/continuous (CGC) perpendicular media consisting of a continuous multilayer structure and a granular layer. The addition of Co/Pt multilayers decreased the nucleation field from 200 to -1800Oe and increased the squareness from 0.9 to 1.0. The moment decay at room temperature was significantly reduced from -4.8% to -0.05% per decade. At elevated temperatures, strong exchange coupling between a granular layer and a continuous layer is needed for thermal stability. The exchange-coupled continuous layer reduces thermal demagnetization as it effectively increases the grain size, tightens the grain distribution, and prevents the reversal of individual grains. Magnetic Force Microscope image showed a larger magnetic cluster size for the CGC structure. Compared to the CoCr18Pt12 medium, the CGC medium had 2.3dB higher output. However, the noise for the CGC medium increased with the recording density, while the noise for the CoCr18Pt12 medium remained constant from 4 to 15kfc/mm. Further optimization and noise reduction are still required for future high density recording.

Original languageEnglish
Pages (from-to)424-428
Number of pages5
JournalJournal of Magnetism and Magnetic Materials
Issue number1-3
Publication statusPublished - 2001 Oct
Externally publishedYes
EventProceedings of the 5th Perpendicular Magnetic Recording Conference (PMRC 2000) - Sendai, Japan
Duration: 2000 Oct 232000 Oct 26


  • Coupled granular/continuous media
  • Perpendicular magnetic recording
  • SNR
  • Thermal stability

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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