Magnetic field dependence of superconducting energy gaps in YNi2B2C: Evidence of multiband superconductivity

TL;DR

This study investigates the magnetic field effects on the superconducting energy gaps in YNi2B2C, providing evidence for multiband superconductivity through directional point contact spectroscopy analysis.

Contribution

It demonstrates the anisotropic behavior of superconducting gaps under magnetic fields and links this to multiband superconductivity in YNi2B2C.

Findings

Energy gap decreases linearly with magnetic field for I||a

Energy gap decreases weakly for I||c with increasing field

Evidence supports multiband superconductivity in YNi2B2C

Abstract

We present results of in field directional point contact spectroscopy (DPCS) study in the quaternary borocarbide superconductor YNi2B2C, which is characterized by a highly anisotropic superconducting gap function. For I||a, the superconducting energy gap (D), decreases linearly with magnetic field and vanishes around 3.25T which is well below the upper critical field (Hc2~6T) measured at the same temperature (2.2K). For I||c, on the other hand, D decreases weakly with magnetic field but the broadening parameter (G) increases rapidly with magnetic field with the absence of any resolvable feature above 3.5T. From an analysis of the field variation of energy gaps and the zero bias density of states we show that the unconventional gap function observed in this material could originate from multiband superconductivity.