Hole pairing and flux quantization in modelCu-O clusters
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In the three-band Hubbard model, the fully symmetric Cu-O clusters with a central Cu and appropriate hole numbers have many-body ground states in which holes are paired. Here we investigate the mechanism of pairing, focusing on clusters with ≤ 21 atoms and 4 holes. We show that spin-flip diagrams yield the effective interaction. The analysis agrees with the results of exact diagonalization and shows that singlet-triplet splitting measures the strength of the pairing interaction. Moreover, the quantization at half-integer values of a magnetic text flux is consistent with supercon-ducting pairing.
PACS 74.60Type-II superconductivity
PACS 31.25Electron correlation calculations for atoms and molecules
PACS 74.20Theories and models of superconducting state
PACS 01.30.EeMonographs and collections
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