Enhanced coherence of antinodal quasiparticles in a dirty d-wave superconductor -: art. no. 214517

Recent angle-resolved photoelectron spectroscopy experiments show a narrow quasiparticle peak at the gap edge along the antinodal [1,0] direction for the overdoped cuprate superconductors. We show that within weak coupling BCS theory for a d-wave superconductor, the s-wave single-impurity scattering cross section vanishes for energies omega=Delta (gap edge). This coherence effect occurs through multiple scattering off the impurity. For small impurity concentrations the spectral function has a pronounced increase of the (scattering) lifetime for antinodal quasiparticles but shows a very broad peak in the nodal direction, in qualitative agreement with the above-mentioned experiment and in strong contrast to the behavior observed in underdoped cuprates.