Remarkable change of tunneling conductance in YBCO films in fields up to 32.4T

TL;DR

This study investigates how strong magnetic fields up to 32.4T affect the tunneling conductance in YBCO films, revealing a significant and reversible shift in the energy gap feature likely caused by surface currents.

Contribution

It provides new insights into the magnetic field-induced changes in the tunneling density of states in YBCO films, highlighting a field-driven transition in the conductance features.

Findings

Discontinuous shift of the gap-like feature from 15meV to 11meV at high fields.

Transition occurs around 9T in increasing fields and around 5T in decreasing fields.

Surface currents induced by magnetic fields drive the observed transition.

Abstract

We studied the tunneling density of states in YBCO 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 $CuO_{2}$ planes. We observed a remarkable change in the tunneling conductance at high fields where the gap-like 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. We argue that this transition is driven by surface currents induced by the applied magnetic field.