# Rod motifs in neutron scattering in spin ice

## TL;DR

This paper explains the origin of rod-like features in neutron scattering in spin ice, showing they result from insensitivity to 3D correlations and clarifying the role of monopole excitations.

## Contribution

It introduces simple models that reproduce scattering rods and clarifies their physical origin and conditions for observation.

## Key findings

- Rod features do not imply absence of inter-plane correlations.
- Neutron scattering sensitivity is limited to certain correlations.
- Monopole excitations influence scattering patterns.

## Abstract

In classical and quantum spin ice, rod-like features appear in the neutron scattering structure factor when the pinchpoints characteristic of classical spin ice get washed out. We show that these features do not indicate the absence of spin correlations between planes perpendicular to the rods. Rather, they arise because unpolarised neutron scattering is largely insensitive to the three-dimensional correlations which are present throughout. We present two very simple models which exhibit a pristine incarnation of such scattering rods. This provides a physical picture for their appearance, elucidates the role played by monopole excitations and identifies conditions conducive to their observation.