Formation of Magnetic Cluster and Remanence Coercivity in Granular-Type Perpendicular Media

T. Shimatsu, T. Oikawa, Y. Inaba, H. Muraoka, Y. Nakamura

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7 Citations (Scopus)


The magnetic cluster size Dcluster of perpendicular recording media, which is a main factor in media noise, is discussed in terms of demagnetizing field of magnetic clusters, remanence coercivity, and magnetization switching. It was shown that the values of remanence coercivity obtained by subtracting thermal agitation effect H0 are ∼70% of those calculated using the Stoner-Wohlfarth model taking account of the c-axis distribution, HrS-W even in CoPtCr-SiO2 media with well segregated grains. Demagnetizing field of magnetic cluster H d is calculated as a function of the ratio of Dcluster to film thickness, δ. An intrinsic remanence coercivity H0 int was obtained by compensating the H0 value by the Hd(H0int = H0 + Hd). The H0int values are very close to those of Hr S-W especially in media with well-segregated grains. This result means that the magnetization reversal of these media is mainly determined by coherent rotation of magnetization; however, the demagnetizing field of magnetic cluster, besides thermal agitation effect, reduces the value of H 0.

Original languageEnglish
Pages (from-to)2335-2337
Number of pages3
JournalIEEE Transactions on Magnetics
Issue number5 II
Publication statusPublished - 2003 Sept


  • Demagnetizing field
  • Magnetic cluster size
  • Magnetization reversal mechanism
  • Perpendicular recording media
  • Remanence coercivity


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