Transition in the tunneling conductance of YBa2Cu3O7-δ films in magnetic fields up to 32.4T

We studied the tunneling density of states in YBa2Cu3O7-δ films under strong currents flowing along node directions. The currents were induced by fields of up to 32.4T parallel to the film surface and perpendicular to the CuO2 planes. We observed an interesting transition in the tunneling conductance at high fields where the gaplike feature shifts discontinuously from 15meV to a lower bias of 11meV, becoming more pronounced as the field increases. The effect takes place in increasing fields around 9T and the transition back to the initial state occurs around 5T in decreasing fields.