Measurement of magnetic excitations in the two-dimensional antiferromagnetic Sr2CuO2Cl2 insulator using resonant x-ray scattering:Evidence for extended interactions

TL;DR

This study uses resonant inelastic x-ray scattering to analyze magnetic excitations in Sr2CuO2Cl2, revealing extended interactions beyond nearest neighbors that influence the magnetic properties of this 2D antiferromagnetic insulator.

Contribution

It provides the first detailed momentum-resolved measurement of magnetic excitations in Sr2CuO2Cl2, demonstrating the significance of extended magnetic interactions in undoped cuprates.

Findings

Identification of single-spin-wave and multi-magnon features.

Large dispersion of spin-waves between zone-boundary points.

Evidence for significant extended electronic hopping in the Hubbard model.

Abstract

Using high-resolution resonant inelastic x-ray scattering (RIXS), we performed a momentum-resolved study of magnetic excitations in the model spin-1/2 2D antiferromagnetic insulator Sr_2CuCl_2O_2. We identify both a single-spin-wave feature and a multi-magnon continuum, and show that the X-ray polarization can be used to distinguish these two contributions in the cross-section. The spin-waves display a large (70 meV) dispersion between the zone-boundary points ($\pi$,0) and ($\pi$/2,$\pi$/2). Employing an extended $t$-$t'$-$t"$-$U$ one-band Hubbard model, we find significant electronic hopping beyond nearest-neighbor Cu ions. We conclude that sizeable extended magnetic interactions are present in \scoc{} and probably important in all undoped cuprates.