TUNNELING IN THE AB PLANE OF THE HIGH-T(C) SUPERCONDUCTOR BI2SR2CACU2O8+DELTA IN HIGH MAGNETIC-FIELDS

Tunneling break junctions of single crystals of Bi-Sr-Ca-Cu-O show a reproducible superconducting-gap structure that can be fully described with a broadened BCS density of states. The obtained ratio between the energy gap DELTA and the critical temperature T(c) amounts to 2DELTA/T(c) = 6.2. In a magnetic field up to 20 T, the conductance curve shows additional broadening but the energy gap remains constant. From a comparison\of the magnetoresistance and tunneling data for different orientations of the magnetic field, it follows that the break junctions probe the superconducting properties in the ab plane. Both the magnetic field and temperature dependence of the tunneling characteristics are in agreement with the known dependences for the classical superconductors.