Fragmented spin ice and multi-$k$ ordering in rare-earth antiperovskites

TL;DR

This paper investigates complex magnetic phases in rare-earth antiperovskites, revealing how frustration and perturbations lead to multi-$k$ ordering and distinctive neutron-scattering signatures.

Contribution

It introduces a theoretical model for rare-earth antiperovskites showing multi-$k$ orders arising from frustration and perturbations, with proposed experimental realizations.

Findings

Identification of a Coulomb phase with dipolar and quadrupolar textures

Discovery of multi-$k$ ordering due to further-neighbour interactions

Predictions of neutron-scattering signatures for experimental detection

Abstract

We study near-neighbour and dipolar Ising models on a lattice of corner-sharing octahedra. In an extended parameter range of both models, frustration between antiferromagnetism and a spin-ice-like three-in-three-out rule stabilises a Coulomb phase with correlated dipolar and quadrupolar spin textures, both yielding distinctive neutron-scattering signatures. Strong further-neighbour perturbations cause the two components to order independently, resulting in unusual multi-$k$ orders. We propose experimental realisations of our model in rare-earth antiperovskites.