Density of States and NMR Relaxation Rate in Anisotropic Superconductivity with Intersecting Line Nodes

Abstract

We show that the density of states in an anisotropic superconductor with intersecting line nodes in the gap function is proportional to $E log (αΔ_0 /E)$ for $|E| << Δ_0$, where $Δ_0$ is the maximum value of the gap function and $α$ is constant, while it is proportional to $E$ if the line nodes do not intersect. As a result, a logarithmic correction appears in the temperature dependence of the NMR relaxation rate and the specific heat, which can be observed experimentally. By comparing with those for the heavy fermion superconductors, we can obtain information about the symmetry of the gap function.