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Micro-Raman study of BiFeO3 thin films fabricated by chemical solution deposition using different Bi/Fe ratio precursors

Takaaki Nakamura 1Hideo Fukumura 1Noriyuki Hasuike 1Hiroshi Harima 1Yoshitaka Nakamura 2Kenji Kisoda 3Seiji Nakashima 4Masanori Okuyama 4

1. Department of Electronics, Kyoto Institute of Technology, Kyoto 606-8585, Japan
2. Institute for Chemical Research, Kyoto University, Kyoto 611-0011, Japan
3. Department of Physics, Wakayama University, Wakayama 640-8510, Japan
4. Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan

Abstract

 Recently, there has been increasing interest in so-called multiferroic materials, where two or more ferroic orderings (ferroelectricity, ferromagnetism and ferroelasticity) coexist simultaneously. In a multiferroic material with ferroelectricity and ferromagnetism, magnetization can be controlled by applied electric field and polarization can be controlled by external magnetic field (magnetoelectric effect). Such materials lead us to future innovative electronic devices. BiFeO3 (BFO) is a promising candidate for such applications because it shows ferroelectric and weak ferromagnetic orderings above room temperature (Curie temperature TC~1100K and Néel temperature TN~640K).

 Recently, the influences of surface texture and Bi/Fe ratios on electric properties of BFO thin films have been investigated.[1] According to [1], two regions with μm-order size were observed on the film surface by atomic force microscopy (AFM). The sample containing lots of one region shows good electric properties. Therefore, in order to improve electric properties of BFO thin films, it is important to investigate their properties in these regions.

 Here, we prepared BFO thin films grown by chemical solution deposition using precursor solutions with different Bi/Fe ratios and were characterized by micro-Raman scattering. Micro-Raman scattering is a very useful tool to study their crystallinity with μm-order spatial resolution. Our Raman results demonstrated that the surface of samples consisted of two regions ; one region crystallized in perovskite units and the other not. These are consistent with AFM observation.[1] We found that the electric properties on BFO thin films are dependent on their crystallinity.

[1] Y.Nakamura, S.Nakashima and M.Okuyama, Jpn. J. Appl. Phys. (submitted)

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2008, Symposium A, by Takaaki Nakamura
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-12 13:57
Revised:   2009-06-07 00:48