BOUND SMALL POLARONS IN HIGH-T<sub>c</sub> SUPERCONDUCTORS
H. SzymczakInstitute of Physics, Polish Academy of Sciences, 02–668 Warsaw, al. Lotnikow 32/46, PolandL. GenzelMax-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 7000 Stuttgart 80, FRGA. WittlinInstitute of Physics, Polish Academy of Sciences, 02–668 Warsaw, al. Lotnikow 32/46, Poland
1990en
ABI
Abstract
The thermal and acoustic anomalies in high-T c superconductors are interpreted in terms of contributions arising from the tunneling motion of bound small polarons. The small polarons arise in YBa 2 Cu 3 O 7 oxides due to the localization of the holes on one of the four O 2− ions surrounding the Cu(2) site in the CuO 2 plane. The optical absorption band located at 0.4 eV is explained as a light-induced transfer of holes between the equivalent O 2− sites. It is argued that the strong hole-lattice interaction is responsible for the enhanced oscillator strength of optical phonons in YBa 2 Cu 3 O 7 .
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