Magnetic property modification of L1/sub 0/ FePt thin films by interfacial diffusion of Cu and Au overlayers

Both Cu-FePt and Au-FePt bilayer thin films were prepared by depositing a Cu or Au cap layer on a fully ordered FePt film at room temperature. A heat treatment at 300/spl deg/C-600/spl deg/C was then applied to the bilayer samples to facilitate interfacial diffusion. For the Cu-FePt system, extensiv...

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Bibliographic Details
Published in:IEEE transactions on magnetics 2005-02, Vol.41 (2), p.921-923
Main Authors: Chen, S.K., Yuan, F.T., Hsiao, Shih-Nan
Format: Article
Language:English
Subjects:
Annealing
Bilayer thin films
Coercive force
coercivity enhancement
FePt
Gold
interfacial diffusion
Magnetic anisotropy
Magnetic films
Magnetic properties
Magnetic recording
Perpendicular magnetic anisotropy
reversal mechanism
Sputtering
Temperature
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Summary:Both Cu-FePt and Au-FePt bilayer thin films were prepared by depositing a Cu or Au cap layer on a fully ordered FePt film at room temperature. A heat treatment at 300/spl deg/C-600/spl deg/C was then applied to the bilayer samples to facilitate interfacial diffusion. For the Cu-FePt system, extensive volume diffusion between L1/sub 0/ FePt and Cu layers occurred as the samples were annealed at 500/spl deg/C and higher temperatures, forming a ternary Fe-Pt-Cu phase with face centered cubic (fcc) structure. As the annealing temperature was lowered to 400/spl deg/C, the diffusion was dominated by grain-boundary mechanism. The best coercivity thus obtained was 14.0 kOe, being 22% larger than that of FePt film without cap layer. For the Au-FePt system, grain-boundary diffusion remains dominant even the annealing temperature is as high as 600/spl deg/C. In both Cu-FePt and Au-FePt bilayer systems, grain-boundary diffusion was found to successfully enhance the coercivity. The /spl Delta/M plot data indicate that incoherent rotation among magnetic grains can be responsible for the high coercivity.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2004.842123