부산대학교 도서관

Until recently, the precise gap function Δ(k) of many nodal superconductors has been unknown. The most notable exception arethe high-temperature cuprate superconductors for which angular resolved photoemission spectroscopy and Josephson interfer-ometry have succeeded to clearly identify dx2. y2-wave symmetry. Unfortunately, it has turned out to be dicult to apply these methods to some of the other nodal superconductors. Recently it has been recognized that the quasiparticle spectrum of nodalsuperconductors in the vortex state is very sensitive to the symmetry of the gap function. In particular, Izawa et al. have succeeded inidentifying an f-wave order parameter in Sr2RuO 4, dx2. y2-wave order in CeCoIn5 and j -ðETÞ2Cu(NCS)2, and s+g-wave super-conductivity in YNi2B2C and PrOs4Sb12. In this paper we review some of the surprises that were encountered in this exploration.