  The pairing state symmetry of the electron-doped cuprate superconductors is
thought to be s-wave in nature, in contrast with their hole-doped counterparts
which exhibit a d-wave symmetry. We re-examine this issue based on recent
improvements in our electron-doped materials and our measurement techniques. We
report microwave cavity perturbation measurements of the temperature dependence
of the penetration depth of Pr_(2-x)Ce_(x)CuO_(4-y) and Nd_(2-x)Ce_(x)CuO_(4-y)
crystals. Our data strongly suggest that the pairing symmetry in these
materials is not s-wave.
