title: Andreev and single-particle tunneling spectra of underdoped cuprate superconductors.
abstract: We study tunneling spectroscopy between a normal metal and an underdoped cuprate superconductor modeled by a phenomenological theory in which the pseudogap is a precursor to the undoped Mott insulator. In the low barrier tunneling limit, the spectra are enhanced by Andreev reflection only within a voltage region of the small superconducting energy gap. In the high barrier tunneling limit, the spectra show a large energy pseudogap associated with single particle tunneling. Our theory semiquantitatively describes the two gap behavior observed in tunneling experiments.
authors.affiliation: Institut fr Theoretische Physik, ETH Zrich, CH-8093 Zrich, Switzerland.
authors.forename: Kai-Yu
authors.initials: KY
authors.lastname: Yang
authors.forename: Kun
authors.initials: K
authors.lastname: Huang
authors.forename: Wei-Qiang
authors.initials: WQ
authors.lastname: Chen
authors.forename: T M
authors.initials: TM
authors.lastname: Rice
authors.forename: Fu-Chun
authors.initials: FC
authors.lastname: Zhang