Rhombohedral (R-) and tetragonal (T-) Bi(Fe,Co)O3 (BFCO) films were epitaxially grown on the SrTiO3 (100) substrates, and the optical properties of the BFCO films were evaluated by spectroscopic ellipsometry. It was revealed that the refractive indexes of R- and T-BFCO epitaxialfilms were 2.93 and 2.86 at wavelength of 600 nm, and 2.65 and 2.59 at 1550 nm, respectively, which are comparable to the pure BiFeO3. The refractive index of the R-BFCO film was totally larger than that of the T-BFCO film; it might be caused by structural strain and local symmetry breaking. It was confirmed that the extinction coefficients of both films were almost zero at wavelengths larger than 600 nm. In addition, the optical band gaps of the R- and T-BFCO films were estimated to be 2.78 and 2.75 eV, respectively. It can expect that the BFCO film has a possibility to use optical-magnetic field sensor working at room temperature.
Received 03 November 2012Accepted 30 November 2012Published online 18 March 2013
This work was partly supported by “Foundation for Promotion of Material Science and Technology of Japan (MST Foundation),” Grant-in-Aid for challenging Exploratory Research (Grant No. 23656025), Strategic International Cooperative Program (Joint Research Type), Japan Science and Technology Agency “Advanced Spintronic Materials and Transport Phenomena (ASPIMATT),” and NEDO Grant.
Article outline: I. INTRODUCTION II. EXPERIMENTAL PROCEDURE III. RESULTS AND DISCUSSION A. Transparent properties B. Model and fitting method C. Estimation of optical constants D. Estimation of optical band gap IV. CONCLUSION
Michio Suzuki and
Source:J. Appl. Phys. 113, 17A914 (
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