Enhancement of ferroelectric and magnetic properties in BiFeO3 films by small amount of cobalt addition

• Published in: Journal of applied physics 2008, Vol.103 (7)
• Main Authors: Naganuma, Hiroshi, Shimura, Nozomi, Miura, Jun, Shima, Hiromi, Yasui, Shintaro, Nishida, Ken, Katoda, Takashi, Iijima, Takashi, Funakubo, Hiroshi, Okamura, Soichiro
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2836971

Both the ferroelectric and magnetic properties of polycrystalline BiFeO3 films fabricated by chemical solution deposition were enhanced by adding small amounts of cobalt. Addition of 3at.% cobalt to BiFeO3 films increased the remanent polarization from 49to72μC∕cm2 and decreased the electric coercive field from 0.54to0.44MV∕cm. The ferroelectricity degraded when the cobalt concentration exceeded 9at.% due to the formation of the secondary phases of Bi2Pt. The saturation magnetization was drastically enhanced by the addition of cobalt up to 12at.%. This is because the magnetic moments are not canceled locally since the differences of magnetic moment between B-sites. The saturation magnetization decreased when the cobalt content exceeded 15at.%, thereby attributing to the formation of a nonmagnetic secondary phase of Bi2Pt. It is concluded that both ferroelectric and magnetic properties were enhanced, provided only small amount of cobalt were added to the films.