Nonmonotonic d sub x sup 2 - sub y sup 2 Superconducting Order Parameter in Nd sub 2-x Ce sub x CuO sub 4

Low energy polarized electronic Raman scattering from electron doped Nd sub 2-x Ce sub x CuO sub 4 single crystal with T sub c = 23 K has been studied using excitation energies from 1.55 to 3.05 eV. The data has been found to be consistent with nonmonotonic d-wave superconducting order parameter with a maximum gap value of 4.2 k sub B T sub c at the Fermi surface intercepts with the antiferromagnetic Brillouin zone (the "hot spots") and a smaller gap value of 3.1 k sub B T sub c at the Brillouin zone boundary.