1. Structural, transport, optical, and electronic properties of Sr2CoNbO6 thin films.
- Author
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Kumar, Ajay, Shukla, Rishabh, Pandey, Akhilesh, Dalal, Sandeep, Miryala, M., Ueno, K., Murakami, M., and Dhaka, R. S.
- Subjects
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THIN films , *PHOTOELECTRON spectroscopy , *INFRARED spectroscopy , *ACTIVATION energy , *DIFFRACTION patterns , *ELECTRO-optical effects , *EPITAXY - Abstract
We study the effect of substrate induced strain on the structural, transport, optical, and electronic properties of Sr 2 CoNbO 6 double perovskite thin films. The reciprocal space mapping, ϕ -scan, and high-resolution θ –2 θ scans of x-ray diffraction patterns suggest the epitaxial nature and high-quality of the films deposited on various single crystal ceramic substrates. A systematic enhancement in the dc electronic conductivity is observed with an increase in the compressive strain while there is a sharp reduction in the case of tensile strain, which is further supported by a change in the activation energy and the density of states near the Fermi level. The optical bandgap extracted from two distinct absorption bands, observed in the visible–near infrared spectroscopy, shows a non-monotonic behavior in the case of compressive strain while there is significant enhancement with tensile strain. Unlike the bulk Sr 2 CoNbO 6 (Co 3 + and Nb 5 + ), we observe different valence states of Co, namely, 2+, 3+, and 4+, and tetravalent Nb (4 d 1) in the x-ray photoemission spectroscopy measurements. Moreover, a reduction in the average oxygen valency with the compressive strain due to enhancement in the covalent character of Co/Nb–O bond is evident. Interestingly, we observe sharp Raman active modes in these thin films, which indicates a significant enhancement in structural ordering as compared to the bulk. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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