J A M Paddison, H Zhang, J-Q Yan, M J Cliffe, S-H Do, S Gao, M B Stone, D Dahlbom, K Barros, C D Batista, A D Christianson, Cubic double perovskites host noncoplanar spin textures, npj Quantum Materials 9, 48 (2024).

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. In this work, we used 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 revealed that these 3-q states are stabilized by biquadratic interactions. Our study identified 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.