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Thickness Dependent Stress Relaxation with the Onset of L10 Ordering in FePt Thin Films

Published online by Cambridge University Press:  01 February 2011

K. W. Wierman ,
C. L. Platt  and
J. K. Howard
K. W. Wierman
Affiliation:
Seagate Research, 1251 Waterfront Place, Pittsburgh, PA 15222–4215.
C. L. Platt
Affiliation:
Seagate Research, 1251 Waterfront Place, Pittsburgh, PA 15222–4215.
J. K. Howard
Affiliation:
Seagate Research, 1251 Waterfront Place, Pittsburgh, PA 15222–4215.
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Abstract

During the chemical ordering of the high anisotropy FePt L10 phase a fcc-→fct structural distortion in the unit cell occurs. Monitoring the stress relaxation time dependencies during isothermal annealing cycles may lead to a better understanding of the L10 ordering kinetics thickness dependencies in thin FePt films. During the isothermal portion of the anneal cycle all films showed an exponentially decaying stress relaxation with time to lower compressive stress states for all temperatures and thickness. The stress relaxation rate increased significantly with an increase in Fe51Pt49 film thickness and annealing temperature. Stress relaxation activation energies of 2.21 eV, 2.40 eV, and 2.96 eV for the 50nm, 25nm, and 10nm Fe51Pt49 films, respectively, were extracted. This correlated well with the observed trends in the post annealed film coercivity, increase of the (001) superlattice L10 peak, and the shifting of the (111) peak position, all indicators of L10 chemical ordering transformation.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 795: Symposium U – Thin Films - Stresses and Mechanical Properties X , 2003 , U5.8
Copyright
Copyright © Materials Research Society 2004

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References

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