Electronic structure of YBa{sub 2}Cu{sub 3}O{sub 7-x}
- Institute of Applied Physics, Kishinev (Moldova, Republic of)
Much attention has been paid to the electronic structure of high-temperature superconductors. The reflection spectra of inorganic materials (even of binary compounds) are known to depend markedly on the condition of their surface. The reflection spectra are especially ambiguous for sputtered layers of ternary (all the more for quaternary) compounds and polished ceramics. This work focuses on the reflection spectra of single-crystal layers of YBa{sub 2}Cu{sub 3}O{sub 7-x} as influenced by annealing, storage time, and position on the surface. The electronic structure of inorganic materials is usually studied by reflection spectra R(E), which allow calculation of the imaginary {epsilon}{sub 2} and real {epsilon}{sub 1} parts of the dielectric constant and other optical functions, as well as by ellipsometry, which allows direct determination of {epsilon}{sub 2}(E) and {epsilon}{sub 1}(E). The application of these methods to high-{Tc} superconductors of the YBa{sub 2}Cu{sub 3}O{sub 7-x} type showed that, in the range 1-5 eV, these spectra exhibited a poorly defined structure. As a rule, within the range 2-5 eV, the reflection is low (R < 0.2), which makes it difficult to discern the features of the spectra. For example, in the range 2-3 eV, the reflectance for the E {parallel} a and E {parallel} b polarizations is the same, the spectrum is almost featureless, and R < 0.1. For this reason, the reflection spectra of single crystals and not only those of films and ceramics may turn out to be of definite interest.
- OSTI ID:
- 75684
- Journal Information:
- Inorganic Materials, Vol. 30, Issue 11; Other Information: PBD: Nov 1994; TN: Translated from Neorganicheskie Materialy; 30: No. 11, 1474-1477(1994)
- Country of Publication:
- United States
- Language:
- English
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