Columnar Structure in FePt-C Granular Media for Heat-Assisted Magnetic Recording

B. S.D.C.S. Varaprasad, J. Wang, T. Shiroyama, Y. K. Takahashi, K. Hono

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


We attempted a compositionally graded sputtering process to overcome the phase separation in the growth direction in the FePt-C granular film in order to realize the columnar structure of FePt grains with an aspect ratio larger than 1.5. In order to overcome the problem of the formation of a second FePt-C layer for the thickness larger than 6 nm, we deposited the FePt-C film by changing the carbon concentration during the sputtering process. The formation of the second FePt-C layer was suppressed, which led to the growth of columnar grains with an aspect ratio of 1.5. The overall volume fraction of carbon is a decisive factor on the size of the FePt grains. Using the compositionally graded process, FePt-C nanogranular films with an average grain size of 7.8 nm, a thickness of 10 nm, and a perpendicular coercivity of 40 kOe were obtained.

Original languageEnglish
Article number7117424
JournalIEEE Transactions on Magnetics
Issue number11
Publication statusPublished - 2015 Nov 1


  • columnar structure
  • FePt-C
  • granular media
  • Heat Assisted Magnetic Recording


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