Effect of Superconductivity on the Incommensurate Magnetic Response of Cuprate Superconductors

TL;DR

This paper demonstrates that a spin-fermion model explains how superconductivity influences the incommensurate magnetic response in cuprates, highlighting the role of d-wave symmetry and Fermi surface topology.

Contribution

It introduces a spin-fermion model that accurately describes the changes in magnetic response due to superconductivity in cuprates, emphasizing their generic features.

Findings

Changes in magnetic response are linked to d-wave symmetry.

The Fermi surface is closed around (π,π) in optimally doped La2-xSrxCuO4.

The model applies broadly to incommensurate magnetic responses in cuprates.

Abstract

We explain the effects of superconductivity on the incommensurate magnetic response $\chi''(q,\omega)$ observed in inelastic neutron scattering measurements on La$_{2-x}$Sr$_x$CuO$_4$. We show that a spin-fermion model correctly describes the frequency and momentum dependent changes of $\chi''$ in the superconducting phase. We find these changes are generic features of an incommensurate spin structure and the d-wave symmetry of the superconducting gap and are thus expected for all cuprates with an incommensurate magnetic response. Our analysis of INS experiments in La$_{2-x}$Sr$_x$CuO$_4$ up to optimal doping suggests a Fermi surface which is closed around $(\pi,\pi)$.