Theory of non-Fermi liquid and pairing in electron-doped cuprates

We apply the spin-fermion model to study the normal state and pairing instability in electron-doped cuprates near the antiferromagnetic quantum-critical point. Peculiar frequency dependencies of the normal state properties are shown to emerge from the self-consistent equations on the fermionic and bosonic self-energies, and are in agreement with experimentally observed ones. We argue that the pairing instability is in the d x2 - y2 channel, as in hole-doped cuprates, but theoretical Tc is much lower than in the hole-doped case. For the same hopping integrals and the interaction strength as in hole-doped materials, we obtain Tc ∼10 K at the end point of the antiferromagnetic phase. We argue that a strong reduction of Tc in electron-doped cuprates compared to hole-doped ones is due to critical role of the Fermi surface curvature for electron-doped materials. The d x2 - y2 -pairing gap Δ(k,ω) is strongly nonmonotonic along the Fermi surface. The position of the gap maxima, however, does not coincide with the hot spots, as the nonmonotonic d x2 - y2 gap persists even at doping when the hot spots merge on the Brillouin zone diagonals.