Nonmonotonic dx22y2 Superconducting Order Parameter in Nd22xCexCuO4
11 March 2002
Low energy polarized electronic Raman scattering of the electron- doped superconductor Nd22xCexCuO4 (x 0.15, Tc 22 K) has revealed a nonmonotonic dx22y2 superconducting order parameter. It has a maximum gap of 4.4kBTc at Fermi surface intersections with an antiferromagnetic Brillouin zone (the "hot spots") and a smaller gap of 3.3kBTc at fermionic Brillouin zone boundaries. The gap enhancement in the vicinity of the hot spots emphasizes the role of antiferromagnetic fluctuations and the similarity in the origin of superconductivity for electron- and hole-doped cuprates.