Neutron scattering in a d_{x^2-y^2}-wave superconductor with strong impurity scattering and Coulomb correlations

TL;DR

This paper models the spin susceptibility in a d_{x^2-y^2}-wave superconductor considering impurity scattering and Coulomb correlations, aligning with some experimental neutron scattering results but predicting narrower peaks than observed.

Contribution

It introduces a theoretical calculation of spin susceptibility that accounts for impurity effects and Coulomb interactions in d-wave superconductors, providing insights into experimental observations.

Findings

Peaks in spin susceptibility are maintained at the zone edge due to impurities and Coulomb correlations.

The suppression of spin susceptibility in the superconducting state aligns qualitatively with experiments.

Predicted peak narrowing in the superconducting state is not observed experimentally.

Abstract

We calculate the spin susceptibility at and below T_c for a d_{x^2-y^2}-wave superconductor with resonant impurity scattering and Coulomb correlations. Both the impurity scattering and the Coulomb correlations act to maintain peaks in the spin susceptibility, as a function of momentum, at the Brillouin zone edge. These peaks would otherwise be suppressed by the superconducting gap. The predicted amount of suppression of the spin susceptibility in the superconducting state compared to the normal state is in qualitative agreement with results from recent magnetic neutron scattering experiments on La_{1.86}Sr_{0.14}CuO_4 for momentum values at the zone edge and along the zone diagonal. The predicted peak widths in the superconducting state, however, are narrower than those in the normal state, a narrowing which has not been observed experimentally.