Disordering of the electronic structure of YBaCuO amorphous films upon incorporation of crystalline clusters formed in laser-induced plasma into their composition |
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Authors: | V D Okunev S J Lewandowski T A D’yachenko A Abal’oshev P Gierłowski V A Isaev |
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Institution: | 1.Galkin Donetsk Institute for Physics and Engineering,National Academy of Sciences of Ukraine,Donetsk,Ukraine;2.Institute of Physics,Polish Academy of Sciences,Warsaw,Poland |
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Abstract: | The effect of crystalline clusters formed in a laser-induced plasma on the optical properties of YBa2Cu3O6 + x
amorphous films prepared by pulsed laser deposition has been investigated. It has been demonstrated that an increase in the
number of clusters leads to a gradual disappearance of interference fringes inherent in optically homogeneous media. Simultaneously,
the incorporation of metallic and insulating clusters into the amorphous medium results in a decrease in the optical band
gap E
0 of the YBaCuO amorphous matrix from 1.28 to 1.06 eV and a considerable decrease in the probability of interband optical transitions
with charge transfer O 2p → Cu 3d due to the loosening of the structure and generation of local stresses. It has been revealed that there is an additional
band gap E
1, which decreases from 0.25–0.30 eV to zero values with a decrease in the optical band gap E
0. The additional gap has been interpreted as an energy gap between localized states that belong to the valence and conduction
bands. A decrease in the density of electronic states in the narrow 3d band leads to the overlap of tails of the density of states, so that the band gap E
1 becomes negative. |
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Keywords: | |
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