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Author Tran, M. Q. ♦ Shapiro, A. L. ♦ Rooney, P. W. ♦ Hellman, F.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ COBALT ALLOYS ♦ PHASE STUDIES ♦ PLATINUM ALLOYS ♦ FILMS ♦ MAGNETIC MATERIALS ♦ PHYSICAL VAPOR DEPOSITION ♦ ANNEALING ♦ MAGNETIC PROPERTIES ♦ SOLUBILITY ♦ SURFACES
Abstract We have deposited (100) and (111) oriented single-crystal Co{sub 1{minus}{ital x}}Pt{sub {ital x}} films ({ital x}=0.65, 0.75, and 0.86) over a range of growth temperatures from {minus}50 to 800{degree}C. The Curie temperature is increased by up to 200{degree}C over the value expected for the homogeneous, chemically disordered alloy in the as-deposited films (of both orientations) grown near 400{degree}C. Measurements of the onset of magnetic ordering below the Curie temperature indicate separation into Co-rich and Pt-rich regions. High resolution x-ray measurements show no shift in the lattice constant or broadening of the x-ray peaks, and no observable strain for {ital x}=0.75, suggesting that the separated regions are small and epitaxially coherent. We interpret this as evidence for a previously unobserved miscibility gap. The bulk phase diagram shows no phase separation, but magnetic energy tends to drive the system toward immiscibility as demonstrated by the calculations of several workers. We suggest that the observed miscibility gap is an equilibrium {ital surface} effect, trapped into the bulk film by low bulk mobility. Preliminary work by Rosengren and Kundrotas supports this idea. Large perpendicular magnetic anistropy is found in those films that exhibit an anomalously high Curie temperature (films grown near 400{degree}C). This anisotropy is likely related to the phase separation. After annealing at high temperatures, the Curie temperature approaches the homogeneous values and the anisotropy relaxes. {copyright} {ital 1996 American Institute of Physics.}
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-04-01
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 79
Issue Number 8
Technical Publication No. CONF-951101-


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