TY - JOUR
T1 - Nanostructure and magnetic properties of FePt
T2 - C cluster films
AU - Xu, Yingfan
AU - Yan, M. L.
AU - Sellmyer, D. J.
N1 - Funding Information:
Manuscript received October 12, 2003. This work was supported by INSIC, NSF-MRSEC, NIST, ARO, Keck Foundation, and NRI. The authors are with the Department of Physics and Astronomy and Center for Materials Research and Analysis, University of Nebraska, Lincoln, NE 68588 USA (e-mail: [email protected]). Digital Object Identifier 10.1109/TMAG.2004.832496
PY - 2004/7
Y1 - 2004/7
N2 - Magnetic properties and nanostructure of FePt: C cluster-deposited films with C volume fraction of 7%, 14%, 33%, and 45% have been studied. As-deposited FePt: C films were prepared by a multilayer method in which FePt layers were deposited from a cluster source employing a gas-aggregation technique and C layers from a normal sputtering gun. In the as-deposited films, FePt clusters with fcc structure are embedded in the C matrix. The high anisotropy FePt L10 cluster structure was realized in the films via post-deposition annealing and the nanostructure of the films was observed by high-resolution transmission electron microscope (TEM). The results for a film with 45 vol. % C showed that FePt clusters are well separated by C matrix and the cluster diameter is about 4.5 nm. The coercivity increases with increase of annealing temperature; coercivities larger than 9 kOe were achieved in the films after annealing at a temperature of 700°C and above. Magnetization reversal of the films was studied by moment-decay measurements and the data were fitted with the Sharrock formula. For the film with 45 vol. % C annealed at 625°C, the thermal stability factor KUV*/kB, T activation volume V*, and anisotropy constant Ku are 231, 0.83 × 101-18cm3 and 1.2 × 107 erg/cm 3, respectively.
AB - Magnetic properties and nanostructure of FePt: C cluster-deposited films with C volume fraction of 7%, 14%, 33%, and 45% have been studied. As-deposited FePt: C films were prepared by a multilayer method in which FePt layers were deposited from a cluster source employing a gas-aggregation technique and C layers from a normal sputtering gun. In the as-deposited films, FePt clusters with fcc structure are embedded in the C matrix. The high anisotropy FePt L10 cluster structure was realized in the films via post-deposition annealing and the nanostructure of the films was observed by high-resolution transmission electron microscope (TEM). The results for a film with 45 vol. % C showed that FePt clusters are well separated by C matrix and the cluster diameter is about 4.5 nm. The coercivity increases with increase of annealing temperature; coercivities larger than 9 kOe were achieved in the films after annealing at a temperature of 700°C and above. Magnetization reversal of the films was studied by moment-decay measurements and the data were fitted with the Sharrock formula. For the film with 45 vol. % C annealed at 625°C, the thermal stability factor KUV*/kB, T activation volume V*, and anisotropy constant Ku are 231, 0.83 × 101-18cm3 and 1.2 × 107 erg/cm 3, respectively.
KW - FePt
KW - High anisotropy
KW - L1 structure
KW - Nanocluster
KW - Thermal stability
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U2 - 10.1109/TMAG.2004.832496
DO - 10.1109/TMAG.2004.832496
M3 - Article
AN - SCOPUS:4444271770
SN - 0018-9464
VL - 40
SP - 2525
EP - 2527
JO - IEEE Transactions on Magnetics
JF - IEEE Transactions on Magnetics
IS - 4 II
ER -