Granular CoPt/C films for high-density recording media (Journal article)

Panagiotopoulos, I./ Stavroyiannis, S./ Niarchos, D./ Christodoulides, J. A./ Hadjipanayis, G. C.

Granular CoPt/C films, consisting of nanoparticles of the face-centered-tetragonal (fct) CoPt phase embedded in a carbon matrix, have been made by cosputtering from CoPt and C targets using a tandem deposition mode. The as-made films have a disordered face-centered-cubic structure and low coercivity (below 100 Oe). The granular structure is obtained after an aging heat treatment, which is followed by a drastic increase in coercivity to values up to 9 kOe due to the formation of the highly anisotropic fct phase. Transmission electron microscope studies showed the size of the CoPt particles to increase from 5 nm in the as-made state to 7-12 nm in the optimally annealed state. The measured coercivities are much lower than the value expected for noninteracting, randomly distributed single-domain particles. The large discrepancy is attributed to interparticle interactions, particle-size effects, and mainly to a lower anisotropy of the fct phase because of incomplete ordering. (C) 2000 American Institute of Physics. [S0021- 8979(00)00909-9].
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Μηχανικών Επιστήμης Υλικών
Keywords: thin-films,coercivity
ISSN: 0021-8979
Link: <Go to ISI>://000086724100051
Publisher: American Institute of Physics
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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