We have fabricated tunnel junctions between chemically etched single crystals of YBa2Cu3O7- and evaporated metal counterelectrodes that exhibit reproducible characteristics. Above the bulk critical temperature of YBa2Cu3O7-, Tc, the conductance as a function of voltage, G(V), has a linear dependence on voltage and some asymmetry. Below Tc, additional structure associated with the superconducting state appears in G(V). At TTc there is a reproducible finite zero-bias conductance, which suggests that there are states at the Fermi energy in superconducting YBa2Cu3O7-. Junctions with Pb, Sn, Bi, Sb, PbBi, and Au counterelectrodes all show qualitatively similar behavior.
|Number of pages||11|
|Journal||Physical Review B|
|State||Published - 1 Jan 1991|