Composition dependence of exchange anisotropy in PtxMn1−x/Co70Fe30 films

We systematically investigated the exchange anisotropy for ferromagnetic Co70Fe30 and antiferromagnetic Pt-Mn bilayer films. We focused on the relevance between the exchange bias and the composition of the PtxMn1−x (14 < x < 22 and 45 < x < 56 at%) films, and we successfully optimized th...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2019-03, Vol.58 (4)
Main Authors: Ranjbar, Sina, Tsunoda, Masakiyo, Oogane, Mikihiko, Ando, Yasuo
Format: Article
Language:English
Subjects:
antiferromagnetic material
exchange anisotropy
PtMn thin film
spintronic applications
unidirectional anisotropy constant
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Summary:We systematically investigated the exchange anisotropy for ferromagnetic Co70Fe30 and antiferromagnetic Pt-Mn bilayer films. We focused on the relevance between the exchange bias and the composition of the PtxMn1−x (14 < x < 22 and 45 < x < 56 at%) films, and we successfully optimized the composition. The crystal structure of the PtxMn1−x films was FCC for 14 < x < 22 at% and FCT for 45 < x < 56 at% after annealing at 370 °C for 6 h. The unidirectional anisotropy constant (Jk) for fcc-Pt15Mn85 (20 nm) and fct-Pt48Mn52 (20 nm) prepared under optimum conditions in composition were 0.16 and 0.20 erg cm−2, respectively. Both Pt15Mn85 and Pt48Mn52 films showed a larger unidirectional anisotropy constant (Jk) than in other reports for the bilayer system that uses Pt-Mn antiferromagnetic layer. They also showed a flatter surface than that of other antiferromagnetic/ferromagnetic materials, which is suitable to avoid unexpected interlayer coupling in spin-valve structure. The obtained Pt-Mn films with a large exchange anisotropy and slight roughness are useful as an antiferromagnetic layer in spintronic applications.
ISSN:0021-4922
1347-4065
DOI:10.7567/1347-4065/ab03e3