Fabrication and characterization of exchange coupled composite media

Jian Ping Wang, Weikang Shen, Soo Youl Hong

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


Magnetic hard and soft phases CoCrPt-SiO2 thin films were developed to fabricate exhange coupled composite (ECC) media. Domain wall nucleation and propagation from the soft regions to the hard regions in the composite grains was found to be the switching mechanism in the ECC media. ECC media on the disk substrate with soft underlayer was fabricated. Interlayer thickness dependence of saturation field and domain wall length in CoCrPt-SiO2 soft layer suggested that domain wall nucleation and propagation in ECC media. Spin-stand testing showed more than a six-times reduction of saturation writing current and more than a 10 dB increase of total signal-to-noise ratio (SNR) for ECC media. Time decay results of readback signals indicated that there is no thermal stability problem for ECC media. The roll-off curve of ECC media showed the same SNR level as a state-of-art reference perpendicular media targeted around 200 Gb/in2. With further optimizations, areal densities beyond 1 Tb/in2 seem achievable for ECC media.

Original languageEnglish (US)
Pages (from-to)682-686
Number of pages5
JournalIEEE Transactions on Magnetics
Issue number2
StatePublished - Feb 2007

Bibliographical note

Funding Information:
This work is being partially supported by Information Storage Industry Consortium (INSIC) Extremely High Density Recording (EHDR) program and Heraeus Inc. The authors would like to thank Emeritus Prof. J. H. Judy at MINT center, University of Minnesota, and Dr. A. Das, M. Racine, and Dr. R. Chen from Heraeus Inc. for their support. The disk substrates with SUL were provided by Dr. S. N. Piramanayagam at Data Storage Institute of Singapore. Disk spin-stand recording performance testing was done by Dr. S. Y. Hong and his colleagues in Samsung Information System America Inc.


  • Coherent switching
  • Domain wall injection
  • Exchange coupled composite (ECC) media
  • Exchange spring media
  • Incoherent switching
  • Perpendicular recording
  • Thermal stability
  • Tilted media
  • Writability


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