Cubic Double Perovskites Host Noncoplanar Spin Textures

TL;DR

This study demonstrates that certain double perovskite materials host noncoplanar 3-q magnetic structures stabilized by biquadratic interactions, revealing their potential for topological magnetism and showcasing neutron spectroscopy as a key diagnostic tool.

Contribution

It provides the first experimental evidence of noncoplanar 3-q states in double perovskites and explains their stabilization mechanism, advancing the understanding of topological magnetic materials.

Findings

Identification of noncoplanar 3-q magnetic structures in Ba2YRuO6 and Ba2LuRuO6

Biquadratic interactions stabilize these 3-q states

Neutron spectroscopy distinguishes multi-q from single-q states

Abstract

Magnetic materials with noncoplanar magnetic structures can show unusual physical properties driven by nontrivial topology. Topologically-active states are often multi-q structures, which are challenging to stabilize in models and to identify in materials. Here, we use inelastic neutron-scattering experiments to show that the insulating double perovskites Ba2YRuO6 and Ba2LuRuO6 host a noncoplanar 3-q structure on the face-centered cubic lattice. Quantitative analysis of our neutron-scattering data reveals that these 3-q states are stabilized by biquadratic interactions. Our study identifies double perovskites as a highly promising class of materials to realize topological magnetism, elucidates the stabilization mechanism of the 3-q state in these materials, and establishes neutron spectroscopy on powder samples as a valuable technique to distinguish multi-q from single-q states, facilitating the discovery of topologically-nontrivial magnetic materials.