Effects of iron concentration and cationic site disorder on the optical properties of magnetoelectric gallium ferrite thin films
- 등재 SCIE, SCOPUS
- 발행기관 Royal Society of Chemistry
- 발행년도 2013
- 총서유형 Journal
- URI http://www.dcollection.net/handler/ewha/000000094635
- 본문언어 영어
- Published As http://dx.doi.org/10.1039/c2ra22681b
초록/요약
Room-temperature dielectric function ε = ε1 + iε2 spectra of magnetoelectric Ga2-xFe xO3 (x = 0.9, 1.0, and 1.4) thin films are determined by spectroscopic ellipsometry (SE) as a function of Fe concentration x. The SE data are analysed by a multilayer model with a series of Tauc-Lorentz oscillators. While the threshold energies slightly decrease as x increases, the oscillator strength shows a strong composition-dependence for the major optical structure at ∼3.5 eV. The experimental data are compared to the ε spectra obtained by density functional theory (DFT) calculations. Even though the overall shape of ε spectra is consistent, the experimental data and calculated spectra show a clear discrepancy in the oscillator's strength ratio of the two optical structures at ∼3.5 and ∼6.0 eV. The DFT calculations suggest that a significant disordering in the cationic (Ga and Fe) sites in Ga2-xFexO3 is present in thin films, which influences their optical properties. This work demonstrates a successful application of optical characterization for determining the cationic sites occupation in thin films, which in turn improves our understanding of Physics and Chemistry in Ga2-xFexO3 thin films and paves a pathway to the development of new multifunctional devices. © 2013 The Royal Society of Chemistry.
more