Enhanced Coherence of Antinodal Quasiparticles in a Dirty d-wave Superconductor

TL;DR

This paper explains the enhanced coherence of antinodal quasiparticles in dirty d-wave superconductors using weak coupling BCS theory, highlighting the role of impurity scattering and its impact on spectral functions.

Contribution

It demonstrates that multiple impurity scattering leads to increased quasiparticle coherence at the antinodes in a d-wave superconductor, aligning theory with recent ARPES experiments.

Findings

Antinodal quasiparticles have increased lifetime due to impurity scattering effects.

Spectral peaks are sharper at antinodes compared to nodal directions.

The theory aligns qualitatively with experimental observations in overdoped cuprates.

Abstract

Recent ARPES 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 of the 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 experiment and in strong contrast to the behavior observed in underdoped cuprates.