BREAK-JUNCTION TUNNELING EXPERIMENTS FOR BI2SR2CACU2OX IN A STRONG MAGNETIC-FIELD

The tunneling conductance curves of single-crystal Bi2Sr2CaCu2Ox break -junctions show a BCS like behaviour with a small leakage current at z ero bias voltage and a reproducible superconducting gap value DELTA = 23 +/- 1 meV. In zero magnetic field the broadening of the tunneling d ata amounts only between 1.5 and 5 meV, depending on the tunneling con tact. The application of a magnetic field up to 20 T leads to a small increase in the broadening of the superconducting gap structure, while the energy position of the gap remains unchanged.