Spectral properties and pseudogap in the stripe phases of cuprate superconductors

Using an exact diagonalization method within the dynamical mean-field theory we analyze the stable stripe structures found in the two-dimensional Hubbard model doped by 0.03<<0.2 holes, and discuss a scenario for stripe melting. Our results demonstrate the importance of dynamical correlations which lead to the metallic stripes, in contrast to the Hartree-Fock picture. The spectral functions show a coexistence of the coherent quasiparticles (polaron band) close to the Fermi energy , and incoherent states at lower energies. The quasiparticles in the polaron band depend on hole doping, and hybridize strongly with the partly filled mid-gap band within the Mott-Hubbard gap, induced by stripe order. This explains the origin of nondispersive quasiparticles close to the Fermi energy mu, observed near the X=(pi ,o) and Y (0,pi) points for the samples with coexisting (10) and (01) stripes. We reproduce the gap which opens for charge excitations at the S =(pi /2,pi /2) point. observed in the angle-resolved photoemission experiments for La2-xSrxCuO4, and a pseudogap in the integrated spectral density pinned to mu, Finally, we show that large spectral weight close to mu moves from the X to the S point when the second neighbor hopping element increases, and the (01) stripe phase is destabilized by kink fluctuations.