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Exchange Coupling and Spin-Flip Transition of CoFe2O4/α-Fe2O3 Bilayered Films

Published online by Cambridge University Press:  21 March 2011

Tatsuo Fujii ,
Takuya Yano ,
Makoto Nakanishi  and
Jun Takada
Tatsuo Fujii
Affiliation:
Department of Applied Chemistry, Faculty of Engineering, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530, Japan
Takuya Yano
Affiliation:
Department of Applied Chemistry, Faculty of Engineering, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530, Japan
Makoto Nakanishi
Affiliation:
Department of Applied Chemistry, Faculty of Engineering, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530, Japan
Jun Takada
Affiliation:
Department of Applied Chemistry, Faculty of Engineering, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530, Japan
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Abstract

CoFe2O4/α-Fe2O3 (ferrimagnetic / antiferromagnetic) bilayered films were prepared on α-Al2O3(102) single-crystalline substrates by helicon plasma sputtering. A well-crystallized epitaxial α-Fe2O3(102) layer was formed on the substrate, while CoFe2O4 grown on α-Fe2O3(102) was a polycrystalline layer with a (100)-preferred orientation. The α-Fe2O3(102) films without CoFe2O4 layers clearly showed a spin-flip transition at about 400 K. The spins aligned perpendicular to the film plane at room temperature changed their direction within the film plane above 400 K. However the α-Fe2O3 base layers of CoFe2O4/α-Fe2O3 bilayered films did not show any spin-flip transition. The CoFe2O4 layer on α-Fe2O3 had a large in-plane magnetic anisotropy, while the spin axis of the α-Fe2O3(102) base layer was directed perpendicular to the film plane. The magnetization of ferrimagnetic CoFe2O4 layers was coupled perpendicularly to the spin axis of anitiferromagnetic α-Fe2O3 layers due to the exchange coupling at the interface between CoFe2O4 and α-Fe2O3.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 674: Symposia T/U/V – Applications of Ferromagnetic and Optical Materials, Storage and Magnetoelectronics , 2001 , T1.10
Copyright
Copyright © Materials Research Society 2001

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References

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