Comparative analysis of specific heat of YNi2B2C using nodal and two-gap models

TL;DR

This study investigates the low-temperature specific heat of YNi2B2C, comparing models to identify the best fit for its superconducting gap, revealing a two-gap structure and nodal features similar to MgB2.

Contribution

It demonstrates that a two-gap model and point-node model best describe YNi2B2C's superconducting gap, providing detailed gap values and field dependence analysis.

Findings

Two-gap model fits the data well.

Electronic specific heat coefficient scales as H^0.47.

Hc2(T) curve shows positive curvature near Tc.

Abstract

The magnetic field dependence of low temperature specific heat in YNi2B2C was measured and analyzed using various pairing order parameters. At zero magnetic field, the two-gap model which has been successfully applied to MgB2 and the point-node model, appear to describe the superconducting gap function of YNi2B2C better than other models based on the isotropic s-wave, the d-wave line nodes, or the s+g wave. The two energy gaps, delta_L=2.67 meV and delta_S=1.19 meV are obtained. The observed nonlinear field dependence of electronic specific heat coefficient, gamma(H)~H0.47, is quantitatively close to gamma(H)~H0.5 expected for nodal superconductivity or can be qualitatively explained using two-gap scenario. Furthermore, the positive curvature in Hc2(T) near Tc is qualitatively similar to that in the other two-gap superconductor MgB2.