Power-law spin correlations in pyrochlore antiferromagnets

TL;DR

This paper demonstrates that in pyrochlore antiferromagnets, spin correlations decay as dipole-dipole interactions due to a zero-divergence polarization field, with results aligning well with simulations and experiments.

Contribution

It introduces a coarse-grained polarization framework to explain spin correlations and diffraction features in pyrochlore antiferromagnets, connecting theoretical predictions with experimental observations.

Findings

Spin correlations decay as 1/|R|^3, resembling dipole interactions.

The derived formula matches neutron scattering data.

Pinch-point singularities are explained by the polarization field.

Abstract

The ground state ensemble of the highly frustrated pyrochlore-lattice antiferromagnet can be mapped to a coarse-grained ``polarization'' field satisfying a zero-divergence condition From this it follows that the correlations of this field, as well as the actual spin correlations, decay with separation like a dipole-dipole interaction ($1/|R|^3$). Furthermore, a lattice version of the derivation gives an approximate formula for spin correlations, with several features that agree well with simulations and neutron-diffraction measurements of diffuse scattering, in particular the pinch-point (pseudo-dipolar) singularities at reciprocal lattice vectors. This system is compared to others in which constraints also imply diffraction singularities, and other possible applications of the coarse-grained polarization are discussed.