Atomic ordering and coercivity mechanism in FePt and CoPt polycrystalline thin films

Citation
S. Jeong et al., Atomic ordering and coercivity mechanism in FePt and CoPt polycrystalline thin films, IEEE MAGNET, 37(4), 2001, pp. 1299-1301
Citations number
11
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
IEEE TRANSACTIONS ON MAGNETICS
ISSN journal
00189464 → ACNP
Volume
37
Issue
4
Year of publication
2001
Part
1
Pages
1299 - 1301
Database
ISI
SICI code
0018-9464(200107)37:4<1299:AOACMI>2.0.ZU;2-E
Abstract
40 nm thick CoPt and FePt films were prepared on oxidized Si substrates wit h 10 nm MgO underlayers. The maximum coercivity (H-c) for CoPt films was fo und to be similar to 10 kOe after annealing at 700 degreesC for similar to 20-30 minutes (min). Structural analysis showed a significant amount of FCC phase as well as the ordered L1(0) phase in these films. FePt films showed an abrupt increase of ordered volume fraction and H-c in the initial stage of annealing and predominance of the tetragonal L1(0) phase after 10 min. at 700 degreesC. The maximum H-c reached similar to 16 kOe after annealing at 700 degreesC for more than 20 minutes. Dark field (DF) images of the ann ealed CoPt films showed individual grains which exhibited a possibility of several variants or disordered phase with dimensions similar to the exchang e correlation length, b(cm). The temperature dependence of H-c seems to ind icate a weak pinning mechanism in the highly ordered FePt films. Magnetic f orce microscopy indicated a complex domain structure consisting of clusters with dimensions of several hundred nanometers.