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Effects of iron concentration and cationic site disorder on the optical properties of magnetoelectric gallium ferrite thin films

Title
Effects of iron concentration and cationic site disorder on the optical properties of magnetoelectric gallium ferrite thin films
Authors
Thomasson A.Ibrahim F.Lefevre C.Autissier E.Roulland F.Meny C.Leuvrey C.Choi S.Jo W.Cregut O.Versini G.Barre S.Alouani M.Viart N.
Ewha Authors
조윌렴
SCOPUS Author ID
조윌렴scopus
Issue Date
2013
Journal Title
RSC Advances
ISSN
2046-2069JCR Link
Citation
vol. 3, no. 9, pp. 3124 - 3130
Indexed
SCIE; SCOPUS WOS scopus
Abstract
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.
DOI
10.1039/c2ra22681b
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자연과학대학 > 물리학전공 > Journal papers
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