Comparative analysis of specific heat of YNi$_{2}$B$_{2}$C using nodal and two-gap models

The magnetic field dependence of low temperature specific heat in YNi$_{2}$B$_{2}$C was measured and analyzed using various pairing order parameters. At zero magnetic field, the two-gap model which has been successfully applied to MgB$_{2 }$and the point-node model, appear to describe the superconducting gap function$_{ }$of YNi$_{2}$B$_{2}$C better than other models based on the isotropic $s$-wave, the $d$-wave line nodes, or the $s+g$ wave. The two energy gaps, \textit{$\Delta $}$_{L}$=2.67 meV and \textit{$\Delta $}$_{S}$=1.19 meV are obtained. The observed nonlinear field dependence of electronic specific heat coefficient, \textit{$\gamma $}($H)\sim H^{0.47},$ is quantitatively close to\textit{ $\gamma $}($H)\sim H^{0.5}_{ }$expected for nodal superconductivity or can be qualitatively explained using two-gap scenario. Furthermore, the positive curvature in $H_{c2}(T)$ near $T_{c}$ is qualitatively similar to that in the other two-gap superconductor MgB$_{2}$.