Exchange coupling in FePt-FePt3nanocomposite films

✍ Scribed by Lin, K.-W. ;Guo, J.-Y. ;Liu, C.-Y. ;Ouyang, H. ;van Lierop, J. ;Phuoc, N. N. ;Suzuki, T.

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 387 KB
• Volume: 204
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200777300

✦ Synopsis

Abstract

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)