Observation of d(x2-y2)-like superconducting gap in an electron-doped high-temperature superconductor

High-resolution angle-resolved photoemission spectroscopy of the electron-d oped high-temperature superconductor Nd2-xCexCuO4 (x = 0.15, transition tem perature T-c = 22 K) has found the quasiparticle signature as well as the a nisotropic d(x2-y2)-like superconducting gap. The spectral line shape at th e superconducting state shows a strong anisotropic nature of the many-body interaction. The result suggests that the electron-hole symmetry is present in the high-temperature superconductors.