A Composite Fermion Model of High-temperature Superconducting Cuprate

A composite fermion model of high-temperature superconducting cuprate is presented, based on the d-p model emphasizing that the electronic state of copper oxides can be described by the fermions constructed with operators newly defined by copper and oxygen holes. The Hamiltonian is so modified by the unitary transformation using these fermion operators as to enable us to apply the mean field approximation. The model reveals that the effective interaction between these composite fermions can determine the pseudogap or the superconductive states, and the Cooper pair formation is created by the interplay between the d-p hybridization and the d-p exchange antiferromagnetic interaction. The properties such as the gap energy and the critical temperature are evaluated by considering the mixed electronic state which composes of the pseudogap and the BCS states.