Hard magnetic properties of rapidly annealed NdFeB thin films on Nb and V buffer layers

H. Jiang, J. Evans, M. J. O'Shea, Jianhua Du

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

NdFeB thin films of the form A (20 nm)/NdFeB(d nm)/A(20 nm), where d ranges from 54 to 540 nm and the buffer layer A is Nb or V were prepared on a Si(1 0 0) substrate by magnetron sputtering. The hard Nd2Fe14B phase is formed by a 30 s rapid anneal or a 20 min anneal. Average crystallite size ranged from 20 to 35 nm with the rapidly annealed samples having the smaller crystallite size. These samples also exhibited a larger coercivity and energy product than those treated by a 20 min vacuum anneal. A maximum coercivity of 26.3 kOe at room temperature was obtained for a Nb/NdFeB (180 nm)/Nb film after a rapid anneal at 725°C. Initial magnetization curves indicate magnetization rotation rather than nucleation of reverse domains is important in the magnetization process. A Brown's equation analysis of the coercivity as a function of temperature allowed us to compare the rapidly annealed and 20 min annealed samples. This analysis suggests that rapid annealing gives higher quality crystalline grains than the 20 min annealed sample leading to the observed large coercivity in the rapidly annealed samples.

Original languageEnglish
Pages (from-to)233-240
Number of pages8
JournalJournal of Magnetism and Magnetic Materials
Volume224
Issue number3
DOIs
StatePublished - 2001

Keywords

  • Coercivity
  • Energy product
  • Permanent magnet
  • Rapid anneal
  • Thin films

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