Pt content dependence of magnetic properties of CoPt/Ru patterned films

K. Mitsuzuka, N. Kikuchi, T. Shimatsu, O. Kitakami, H. Aoi, H. Muraoka, J. C. Lodder

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6 Citations (Scopus)


The magnetic properties of dot arrays made of CoPt/Ru perpendicular films (20 nm thickness) were examined as a function of Pt content. The CoPt dot arrays with a dot size D of 140 nm showed a single domain state, after removal of the applied field equal to Hr. Hr decreased from 5.2 kOe to 3.0 kOe as the Pt content decreased from 20 at% to 14 at%. The angular dependence of Hr for these dot arrays indicated coherent rotation of the magnetization during nucleation. The effective magnetic anisotropy, including the demagnetizing energy due to the dot shape, Ku eff, decreased as the Pt content decreased, resulting in the H r reduction. The values of the switching volume for nucleation, Vsw, evaluated from the stabilizing energy barrier E0, were a few percent of the dot volume. The switching diameter for nucleation, Dsw, increased slightly as the Pt content decreased, which was qualitatively in good agreement with the increase in the exchange length of magnetization. The value of E0/kBT (kB is the Boltzmann constant and T is the absolute temperature) reduced as the Pt content decreased; however, E0/kBT still had a high of 440 even at 14 at% Pt content. We successfully demonstrated the reduction of Hr for CoPt/Ru patterned films on reducing the Pt content, while simultaneously maintaining a high thermal stability. A calculation based on the experimental results suggested the potential recording density of CoPt/Ru dot arrays used for patterned media to be over 1 Tb/in2.

Original languageEnglish
Pages (from-to)3883-3885
Number of pages3
JournalIEEE Transactions on Magnetics
Issue number12
Publication statusPublished - 2006 Dec


  • CoPt/Ru perpendicular films
  • Dot arrays
  • Patterned media
  • Remanence coercivity
  • Single domain
  • Thermal stability


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