A new mechanism is proposed for electron pairing in a series of oxide superconductors Ln1Ba2Cu3O7-x (LN=Y and Lanthanide element). This mechanism takes advantage of the triple plane-chain-plane structure, with essential use of antiferromagnetic interlayer superexchange and Kondo type intralayer exchange interactions. A Cooper pair is formed between two oxygen holes belonging to neighboring Cu-O planes, via singlet-triplet excitations in the localized Cu-Cu spin pairs. This mechanism is shown to be consistent with main features of various experiments. A small but finite isotope effect is also derived.
ASJC Scopus subject areas
- Condensed Matter Physics