L1{sub 0} phase transformation and magnetic behaviors of (Fe, FePt, FePtCu)-C nanocomposite films

Journal Article · Wed Jun 15 00:00:00 EDT 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1929089· OSTI ID:20711767

Mi, W B; Hui, Liu; Li, Z Q; Wu, P; Jiang, E Y; Bai, H L ^[1]

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1. Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Institute of Advanced Materials Physics, Faculty of Science, Tianjin University, Tianjin 300072 (China)

As-deposited (Fe, FePt, FePtCu)-C nanocomposite films with fixed C atomic fraction x{sub c}=47 fabricated using facing-target sputtering method at room temperature are composed of {approx}2-3-nm amorphous metal granules buried in a-C matrix. Annealing at high temperatures turns the amorphous granules into {alpha}-Fe, {alpha}-Fe- and L1{sub 0}-structured FePt, and L1{sub 0}-ordered FePtCu for Fe-C, FePt-C, and FePtCu-C films, respectively, and makes a-C preferential graphitization. As-deposited granules are superparamagnetic at 300 K, and ferromagnetic at 5 K. The zero-field-cooled (ZFC) and field-cooled (FC) curves reveal that there exist strong intergranular interactions at temperatures below 300 K, and the size distribution of granules becomes broad by Pt and Cu addition. The M-H loop of annealed Fe{sub 31}Pt{sub 22}C{sub 47} films exhibits a two-step saturation behavior because of the coexistence of soft and hard ferromagnetic phases. As the Cu atomic fraction is 14%, the coercivity of annealed Fe{sub 23}Pt{sub 16}Cu{sub 14}C{sub 47} films reaches a large value of {approx}11.2 kOe at 5 K and decreases to {approx}7.2 kOe at 300 K.

• OSTI ID: 20711767
• Journal Information: Journal of Applied Physics, Vol. 97, Issue 12; Other Information: DOI: 10.1063/1.1929089; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
CARBON
COERCIVE FORCE
COMPOSITE MATERIALS
COPPER ALLOYS
DEPOSITION
FERROMAGNETIC MATERIALS
GRAPHITIZATION
IRON ALLOYS
IRON-ALPHA
ORDER-DISORDER TRANSFORMATIONS
PLATINUM ALLOYS
SPUTTERING
SUPERPARAMAGNETISM
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
THIN FILMS