Order parameter node removal in the d-wave superconductor $YBa_{2}Cu_{3}O_{7-x}$ under magnetic field

TL;DR

This paper investigates whether an applied magnetic field can remove the nodes in the d-wave order parameter of the high-temperature superconductor YBa2Cu3O7-x, providing new tunneling data that supports the occurrence of node removal under specific conditions.

Contribution

It presents new tunneling measurements on YBa2Cu3O7-x that support the possibility of node removal in the d-wave superconductor under magnetic fields, clarifying previous conflicting results.

Findings

Support for node removal in YBa2Cu3O7-x under magnetic field

Explanation of hysteresis effects in tunneling data

Identification of conditions for node removal based on surface and field orientation

Abstract

hether the node in the order parameter characteristic of a $d-wave$ superconductor can or cannot be removed by an applied magnetic field has been a subject of debate in recent years. Thermal conductivity results on the high Tc superconductor $Bi_{2}Sr_{2}CaCu_{2}O_{8}$ originally explained by Laughlin in terms of such a node removal were complicated by hysteresis effects, and judged inconclusive. We present new tunneling data on $YBa_{2}Cu_{3}O_{7-x}$ that support the existence of the node removal effect, under specific orientations of the sample's surfaces and magnetic field. We also explain the hysteretic behavior and other previous tunneling results so far not understood satisfactorily, attributing them to a combination of node removal and Doppler shift of low energy surface bound states.