THEORY OF THE PSEUDOGAP IN THE ELEMENTARY EXCITATION SPECTRUM OF THE NORMAL-PHASE OF BILAYER CUPRATES

Solutions of the integral equations for the pseudogap in the elementar y excitation spectrum of current carriers in bilayer cuprates are foun d. In the general case, the pseudogap possesses s + id symmetry, where the s component is determined by the interaction of holes via the pho non held and the d component is due to the superexchange interaction o f the copper spins and the Coulomb-repulsion screened holes. The s and d components exhibit different temperature dependences. This fact ena bled us to explain the characteristic features of the temperature beha vior of the normal-phase spin susceptibility of lightly doped cuprates , specifically, for the compound YBa2Cu4O8 in the entire temperature i nterval T > T-c. The wave-number dependence of the pseudogap agrees wi th the photoemission data for Bi2Sr2CaCu2O8+y. (C) 1997 American Insti tute of Physics.