Spectral properties and pseudogap in the stripe phases of cuprate superconductors - art. no. 134528

Using an exact diagonalization method within the dynamical mean-field theor y we analyze the stable stripe structures found in the two-dimensional Hubb ard model doped by 0.03<<delta><0.2 holes, and discuss a scenario for strip e melting. Our results demonstrate the importance of dynamical correlations which lead to the metallic stripes, in contrast to the Hartree-Fock pictur e. The spectral functions show a coexistence of the coherent quasiparticles (polaron band) close to the Fermi energy <mu>, and incoherent states at lo wer 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 nondispe rsive 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) strip es. We reproduce the gap which opens for charge excitations at the S =(pi / 2,pi /2) point. observed in the angle-resolved photoemission experiments fo r La2-xSrxCuO4, and a pseudogap in the integrated spectral density pinned t o mu, Finally, we show that large spectral weight close to mu moves from th e X to the S point when the second neighbor hopping element increases, and the (01) stripe phase is destabilized by kink fluctuations.