Highly spin-polarized current in Co-substituted Fe{sub 3}O{sub 4} epitaxial thin films at room temperature

Journal Article · Sun Dec 07 04:00:00 UTC 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4903215· OSTI ID:22402725

Takahashi, Masanao; Ohshima, Toshiyuki; Yamahara, Hiroyasu; Seki, Munetoshi; Tabata, Hitoshi ^[1]

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1. Department of Electrical Engineering and Information Systems, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

Epitaxial thin films of cobalt ferrite Co{sub x}Fe{sub 3−x}O{sub 4} (x = 0.0, 0.5, and 1.0) were fabricated on α-Al{sub 2}O{sub 3} (001) substrates using pulsed laser deposition. It was found that the coercive force of the cobalt ferrite films could be tuned by changing the Co content. The films prepared under low oxygen pressure (1.0 × 10{sup −6 }Pa) showed semiconducting behavior even for x = 1.0. X-ray photoelectron spectroscopy revealed that the Co ions were 2{sup +} for all compositions. On the other hand, it was found that the Fe ions were in the Fe{sup 2+}/Fe{sup 3+} valence state, which may cause small-polaron hopping among the Fe-3d electrons in the films. An anomalous Hall effect was observed in the Co{sub 0.5}Fe{sub 2.5}O{sub 4} film even at 300 K, suggesting that carriers in the films were highly spin-polarized at room temperature.

• OSTI ID: 22402725
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 21 Vol. 116; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM OXIDES
COBALT
COBALT IONS
COERCIVE FORCE
ENERGY BEAM DEPOSITION
EPITAXY
FERRITES
HALL EFFECT
IRON IONS
IRON OXIDES
LASER RADIATION
PULSED IRRADIATION
SPIN ORIENTATION
SUBSTRATES
TEMPERATURE RANGE 0273-0400 K
THIN FILMS
VALENCE
X-RAY PHOTOELECTRON SPECTROSCOPY