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Microstructure and Magnetic Property of L1o CoPt–20 at.% C Magnetic Thin Film

Published online by Cambridge University Press:  10 February 2011

D. Y. Oh  and
J. K. Park
D. Y. Oh
Affiliation:
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373–1 Kusong-dong, Yusong-gu, Daejeon, 305–701, Korea.
J. K. Park
Affiliation:
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373–1 Kusong-dong, Yusong-gu, Daejeon, 305–701, Korea.
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Abstract

The CoPt-20at.%C thin films of 20nm thickness were sputter-deposited in the form of CoPt/Cn (n=1: carbon layer thickness=4nm; n=4: each carbon layer thickness=1nm) and were transformation-annealed at 650°C for various times. Carbon was found to dissolve into CoPt lattice and enlarge the c/a ratio of the ordered CoPt lattice. The amount of carbon dissolution increases with the decreasing carbon layer thickness at a given total carbon concentration.

The carbon dissolution larger than a critical amount can lead to a shift of the phase equilibrium of ordering and produce a stable fine two-phase mixture of ordered and disordered phases at the equi-atomic composition of Co:Pt. This results in a fine and uniform stagnant grain structure of about 20nm on annealing at 650°C. The carbon dissolution by increasing the c/a ratio of the ordered CoPt lattice reduces both the saturation magnetization and the magnetocrystalline anisotropy constant of the film and leads to a reduction of coercivity of CoPt films.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 746: Symposia Q/R – Magnetoelectronics-Novel Magnetic Phenomena in Nanostructures – Advanced Characterization of Artificially Structured Magnetic Materials , 2002 , Q2.5
Copyright
Copyright © Materials Research Society 2003

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References

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