Field Induced Nodal Order Parameter in the Tunneling Spectrum of YBa$_2$Cu$_3$O$_{7-x}$ Superconductor

TL;DR

This study uses tunneling measurements on YBa2Cu3O7-x thin films to reveal a doping-sensitive, field-induced energy scale near the d-wave node, suggesting an induced idxy order parameter at optimal doping.

Contribution

It demonstrates the existence of a field-induced energy scale linked to an induced idxy order parameter in YBa2Cu3O7-x, with doping-dependent behavior.

Findings

Energy scale dominates near the d-wave node.

High doping sensitivity of the energy scale.

Agreement with induced idxy order parameter at optimal doping.

Abstract

We report planar tunneling measurements on thin films of YBa$_2$Cu$_3$O$_{7-x}$ at various doping levels under magnetic fields. By choosing a special setup configuration, we have probed a field induced energy scale that dominates in the vicinity of a node of the d-wave superconducting order parameter. We found a high doping sensitivity for this energy scale. At Optimum doping this energy scale is in agreement with an induced $id_{xy}$ order parameter. We found that it can be followed down to low fields at optimum doping, but not away from it.