Eur. Phys. J. B (2016) 89: 91
https://doi.org/10.1140/epjb/e2016-60849-4

Regular Article

Pseudogaps in the three-band Hubbard model

Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu, Estonia

^a e-mail: alekseis@ut.ee

Received: 27 October 2015
Received in final form: 12 December 2015
Published online: 6 April 2016

Abstract

Using the strong coupling diagram technique, the energy spectrum of the three-band Hubbard model is investigated. In these calculations, the series in powers of the copper-oxygen hybridization for the irreducible part is approximated by two lowest-order terms. For parameters of hole-doped cuprates the calculated energy spectrum consists of lower and upper Hubbard subbands of predominantly copper nature, oxygen bands with some admixture of copper states and the Zhang-Rice states of mixed nature. The spectrum contains two pseudogaps, the lower of which separates the Hubbard subband from Zhang-Rice and oxygen bands. The pseudogaps arise due to multiple reabsorption of carriers in states with double occupancy of sites by holes or electrons.