Nonmonotonic dx2-y2 superconducting gap in electron-doped Pr0.89LaCe0.11CuO4:: Evidence of coexisting antiferromagnetism and superconductivity?

Recent experiments on Pr0.89LaCe0.11CuO4 observe an anisotropic spin-correlation gap and a nonmonotonic superconducting (SC) gap, which we analyze within the framework of a t-t(')-t(')-t(')-t(iv)-U model with a d(x)(2)-y(2) pairing interaction including a third-harmonic contribution. By introducing a realistic broadening of the quasiparticle spectrum to reflect small-angle scattering, our computations explain the experimental observations, especially the presence of a maximum in the leading-edge gap in the vicinity of the hot spots. Our analysis suggests that the material behaves like a two-band superconductor with the d-wave third harmonic acting as the interband pairing gap, and that the antiferromagnetic and SC orders coexist in a uniform phase.