Ta Doping Effect in Co60C40 Thin Films

Y. Zhao, T. J. Zhou, J. P. Wang, T. C. Chong

Research output: Contribution to journalArticlepeer-review


(Co60C40)1-x Tax films (0% ≤ x ≤ -10%) with thickness of 30 nm were cosputtered onto C-buffered glass substrates at room temperature. The as-deposited films are structurally amorphous and nonferromagnetic. The annealed films (400 ° for 30 min) become magnetically hard with Hc ranging from 480 to 780 Oe and Ms changing from 480 to 600 emu/cm3. Both Hc and Ms increase with Ta concentration as x < 3%, show peaks at x = 3%, and then decrease with Ta concentration. This is because a small amount of Ta doping might enhance the diffusion of carbon in the films and thus form more cobalt grains upon annealing. However, doping more Ta (x > 3%) destroys the Co structure and this causes the drop in both Hc and Ms. After annealing at 300 °, Hc of (Co60C 40)97Ta3 films increases from 0 to about 380 Oe, while almost no changes are observed for Co60 C40 films. Doping in a Co-C system with a larger atom such as Ta may be a way to enhance the segregation of Co and C and, therefore, reduce phase segregation temperature.

Original languageEnglish (US)
Pages (from-to)2702-2704
Number of pages3
JournalIEEE Transactions on Magnetics
Issue number5 II
StatePublished - Sep 2003


  • Carbon
  • Cobalt
  • Magnetic recording media
  • Phase segregation
  • Ta doping


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