Normal-state pseudogap in the spectrum of strongly correlated fermions

Recently a pseudogap with d-wave symmetry was observed near the Fermi level in photoemission spectra of normal-state Bi₂Sr₂CaCu₂O₈ 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≲0.17 and the pseudogap disappears in optimally and overdoped crystals when x≳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.