Microwave Electrodynamics of the Electron-Doped Cuprate Superconductors Pr_(2-x)Ce_(x)CuO_(4-y) and Nd_(2-x)Ce_(x)CuO_(4-y)

摘要

The pairing state symmetry of the electron-doped cuprate superconductors isthought to be s-wave in nature, in contrast with their hole-doped counterpartswhich exhibit a d-wave symmetry. We re-examine this issue based on recentimprovements in our electron-doped materials and our measurement techniques. Wereport microwave cavity perturbation measurements of the temperature dependenceof 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 thesematerials is not s-wave.