Theory for electron-doped cuprate superconductors:d-wave symmetry order parameter

Using as a model the Hubbard Hamiltonian we determine various basic properties of electron-doped cuprate superconductors like ${\mathrm{Nd}}_{2-x}{\mathrm{Ce}}_x{\mathrm{CuO}}_4$ and ${\mathrm{Pr}}_{2-x}{\mathrm{Ce}}_x{\mathrm{CuO}}_4$ for a spin-fluctuation-induced pairing mechanism. Most importantly we find a narrow range of superconductivity and, similar to hole-doped cuprates $d_{x^2-y^2},$ symmetry for the superconducting order parameter. The superconducting transition temperatures $T_c\mathrm{}\left(x\right)\mathrm{}$ for various electron doping concentrations x are calculated to be much smaller than for hole-doped cuprates due to the different energy dispersion and a flat band well below the Fermi level. Lattice disorder may sensitively distort the symmetry $d_{x^2-y^2}$ via electron-phonon interaction.