Fabrication and characterization of fept exchange coupled composite and graded bit patterned media

Hao Wang, Haibao Zhao, Tofizur Rahman, Yousuke Isowaki, Yoshiyuki Kamata, Tomoyuki Maeda, Hiroyuki Hieda, Akira Kikitsu, Jian Ping Wang

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Three methods to fabricate continuous FePt films with graded magnetic anisotropy for bit patterned media (BPM) were evaluated. Continuous FePt films with surface roughness of less than 0.3 nm were achieved in continuous FePt hard magnetic films, FePt/Fe exchange coupled composite (ECC) films and FePt/Fe based graded films. Depositing an Fe-rich film on FePt at high temperature was found to form large grains and cause the film surface very rough for BPM fabrication. Depositing Fe on FePt at room temperature and then annealing it to create graded anisotropy through the layer interdiffusion process was demonstrated to fabricate FePt/Fe based graded BPM. The continuous FePt films with hard layer only, ECC structure and graded magnetic anisotropy were patterned using a di-block copolymer self-assemble hard mask method with 25 nm dot size over 2-inch substrate. The switching field distribution (SFD) broadening and degradation of FePt BPM was studied. The reduction of SFD was achieved using a postannealing process. It was confirmed that the patterned graded BPM sample has smaller switching field and larger thermal energy barrier than the ECC sample.

Original languageEnglish (US)
Article number6417007
Pages (from-to)707-712
Number of pages6
JournalIEEE Transactions on Magnetics
Issue number2
StatePublished - 2013


  • Bit patterned media
  • FePt media
  • FePt thin films
  • block copolymer lithograph
  • etching damage
  • exchange coupled composite media
  • graded media
  • switching field distribution


Dive into the research topics of 'Fabrication and characterization of fept exchange coupled composite and graded bit patterned media'. Together they form a unique fingerprint.

Cite this