Determination of the superconducting gap in YBa2Cu3O7-δ by tunneling experiments under magnetic fields

We have measured the characteristics of [110]- and [100]-oriented YBa2Cu3O7-delta,/insulator/In tunnel junctions under applied magnetic fields. The comparison between the conductance characteristics ae zero field and the characteristics at high fields enables us to discriminate between the superconducting energy gap and features that are unrelated to superconductivity, and to determine the gap value.