Gap Symmetry of Superconductivity in UPd2Al3
The angle dependent thermal conductivity of the heavy-fermion superconductor UPd$_2$Al$_3$ in the vortex state was recently measured by Watanabe et al. Here we analyze this data from two perspectives: universal heat conduction and the angle-dependence. We conclude that the superconducting gap function $Δ({\bf k})$ in UPd$_2$Al$_3$ has horizontal nodes and is given by $Δ({\bf k}) =Δ\cos(2χ)$, with $χ= ck_{z}$.
cond-mat.supr-con↗