Normal-state pseudogap in the spectrum of strongly correlated fermions

Abstract

Recently a pseudogap with d-wave symmetry was observed near the Fermi level in photoemission spectra of normal-state ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ crystals. We demonstrate that an analogous pseudogap exists in the energy spectrum of the two-dimensional t-J model of cuprate perovskites. In agreement with experiment the magnitude of the pseudogap is 10--20 meV in underdoped crystals with hole concentration x\ensuremath{\lesssim}0.17 and the pseudogap disappears in optimally and overdoped crystals when x\ensuremath{\gtrsim}0.17. We demonstrate also that in the t-J model the overall energy spectrum near the Fermi level and the Fermi surface agree well with experimental observations.