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 zero bias voltage and a reproducible superconducting gap value Δ = 23 ± 1 meV. In zero magnetic field the broadening of the tunneling data amounts only between 1.5 and 5 meV, depending on the tunneling contact. 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. (orig.)