Tunneling spectra of submicron Bi2Sr2CaCu2O8+δ intrinsic Josephson junctions: evolution from superconducting gap to pseudogap

AbstractTunneling spectra of near optimally doped, submicron Bi2Sr2CaCu2O8+δ intrinsic Josephson junctions are presented, and examined in the region where the superconducting gap evolves into pseudogap. The spectra are analyzed using a self-energy model, proposed by Norman et al., in which both quasiparticle scattering rate Γ and pair decay rate ΓΔ are considered. The density of states derived from the model has the familiar Dynes’ form with a simple replacement of Γ by γ+ = (Γ+ΓΔ)/2. The γ+ parameter obtained from fitting the experimental spectra shows a roughly linear temperature dependence, which puts a strong constraint on the relation between Γ and ΓΔ. We discuss and compare the Fermi arc behavior in the pseudogap phase from the tunneling and angle-resolved photoemission spectroscopy experiments. Our results indicate an excellent agreement between the two experiments, which is in favor of the precursor pairing view of the pseudogap.