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Correlated Pair‐Transfer Mechanism for High Temperature Superconductivity. The Case of YBa 2 Cu 3 O 6+ x
Author(s) -
Sinha K. P.,
Singh M.
Publication year - 1990
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221590226
Subject(s) - superconductivity , condensed matter physics , pairing , physics , excited state , transition temperature , high temperature superconductivity , symmetry (geometry) , electron , electron transfer , superconducting transition temperature , crystallography , chemistry , atomic physics , quantum mechanics , geometry , mathematics
A theoretical study of high temperature superconductivity in the system YBa 2 Cu 3 O 6+ x is made using the correlated pair transfer mechanism suggested recently. The mechanism involves the role of electron pairs in the spin singlet state of species \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm X}^{\uparrow \downarrow } (= {\rm Cu}^{{\rm 1 + }},{\rm O}_{\rm 2}^{{\rm 2 - }} {\rm, or O}^{{\rm 2 - }} {\rm)} $\end{document} and their virtual excited state X 0 (Cu 3+ , O 2 0 , or O 0 ) in the pairing interaction of quasiholes. The two states of these species can be likened to a two‐level Bose system. The strength of the interaction depends on the hole and species concentration. The expression for the transition temperature is a combination of phononic and the electronic mechanism and the calculated trend as a function of hole concentration (in effect excess O − ) is in agreement with the observed trend. The mechanism is applicable to other oxide systems where such variable species can exist (e. g. Bi 3+ , Bi 5+ or Tl 1+ , Tl 3+ , etc.). The theory has electron and hole symmetry, therefore it can also be applied to n‐type high temperature superconductors.