Compositional modulated atomic layer stacking and uniaxial magnetocrystalline anisotropy of CoPt alloy sputtered films with close-packed plane orientation
- Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 6-6-05, Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)
- New Industry Creation Hatchery Center, Tohoku University, 6-6-10, Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)
- Foundation for Promotion of Material Science and Technology of Japan, 1-18-6 Kitami, Setagaya-ku, Tokyo 157-0067 (Japan)
An atomic layer stacking structure in hexagonal close packed (hcp) Co{sub 100−x}Pt{sub x} alloy films with c-plane sheet texture was directly observed by a high-angle annular dark-field imaging scanning transmission electron microscopy. The analysis of sequential and/or compositional atomic layer stacking structure and uniaxial magnetocrystalline anisotropy (K{sub u} = K{sub u1} + K{sub u2}) revealed that (1) integrated intensity of the superlattice diffraction takes the maximum at x = 20 at. % and shows broadening feature against x for the film fabricated under the substrate temperature (T{sub sub}) of 400 °C. (2) Compositional separation structure in atomic layers is formed for the films fabricated under T{sub sub} = 400 °C. A sequential alternative stacking of atomic layers with different compositions is hardly formed in the film with x = 50 at. %, whereas easily formed in the film with x = 20 at. %. This peculiar atomic layer stacking structure consists of in-plane-disordered Pt-rich and Pt-poor layers, which is completely different from the so-called atomic site ordered structure. (3) A face centered cubic atomic layer stacking as faults appeared in the host hcp atomic layer stacking exists in accompanies with irregularities for the periodicity of the compositional modulation atomic layers. (4) K{sub u1} takes the maximum of 1.4 × 10{sup 7 }erg/cm{sup 3} at around x = 20 at. %, whereas K{sub u2} takes the maximum of 0.7 × 10{sup 7 }erg/cm{sup 3} at around x = 40 at. %, which results in the maximum of 1.8 × 10{sup 7 }erg/cm{sup 3} of K{sub u} at x = 30 at. % and a shoulder in compositional dependence of K{sub u} in the range of x = 30–60 at. %. Not only compositional separation of atomic layers but also sequential alternative stacking of different compositional layers is quite important to improve essential uniaxial magnetocrystalline anisotropy.
- OSTI ID:
- 22410048
- Journal Information:
- Journal of Applied Physics, Vol. 117, Issue 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
COBALT ALLOYS
CONCENTRATION RATIO
DIFFRACTION
FCC LATTICES
HCP LATTICES
LAYERS
MODULATION
ORIENTATION
PERIODICITY
PLATINUM ALLOYS
SCANNING ELECTRON MICROSCOPY
SPUTTERING
SUBSTRATES
SUPERLATTICES
TEXTURE
TRANSMISSION ELECTRON MICROSCOPY