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Exchange coupling in FePt‐FePt 3 nanocomposite films
Author(s) -
Lin K.W.,
Guo J.Y.,
Liu C.Y.,
Ouyang H.,
van Lierop J.,
Phuoc N. N.,
Suzuki T.
Publication year - 2007
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200777300
Subject(s) - annealing (glass) , coercivity , materials science , nanocomposite , transmission electron microscopy , exchange bias , analytical chemistry (journal) , magnetization , condensed matter physics , metallurgy , nanotechnology , magnetic field , chemistry , magnetic anisotropy , physics , chromatography , quantum mechanics
In this study, the structural and magnetic properties of exchange coupled nanocomposite FePt‐FePt 3 films were investigated. X‐ray diffraction and transmission electron microscopy results showed that after rapid thermal annealing (600 °C for 6 minutes), a phase transformation from [Pt+Fe] into composite FePt‐FePt 3 phases was obtained. Annealing created an ordered FePt phase that resulted in a large room temperature coercivity (H c ∼ 3200 Oe) compared to the as‐deposited film (H c ∼ 20 Oe). While no exchange bias field (H ex ∼ 0 Oe) was measured at room temperature, the annealed sample showed significant H ex ∼ ‐500 Oe at lower temperatures (150 K ≤ T ≤ 250 K), indicative of exchange coupling between FePt and FePt 3 . The high blocking temperature (∼250 K) indicates FePt 3 exhibits an enhanced Néel temperature. Further increasing the annealing temperature to 700 °C resulted in a reduction of H ex which is attributed to the transformation of FePt 3 into the FePt phase at this higher annealing temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)