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Schrieffer‐Wolff Transformation of the Emery Model for Cu–O Superconductors
Author(s) -
Kolley E.,
Kolley W.
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.2221570140
Subject(s) - superexchange , spins , superconductivity , hamiltonian (control theory) , condensed matter physics , canonical transformation , exchange interaction , physics , t j model , amplitude , mathematical physics , quantum mechanics , mathematics , ferromagnetism , hubbard model , quantum , mathematical optimization
The minimal version of the Emery model – ascribed to a CuO 2 layer in high‐ T c superconductors – is subject to a canonical transformation of the Schrieffer‐Wolff type up to the fourth order in the hybridization amplitude. An effective Hamiltonian is extracted systematically consisting of three parts: the kinetic energy of O‐holes, a Kondo‐like Cu–O exchange interaction, and the Heisenbergtype superexchange interaction between localized Cu spins with a modified coupling parameter in the undoped case. The assumptions and approximations underlying the derivation of the t̃– J pd – J dd model are pointed out.