Cubic double perovskites host noncoplanar spin textures
Joseph A. M. Paddison, Hao Zhang, Jiaqiang Yan, Matthew J. Cliffe, Michael A. McGuire, Seung-Hwan Do, Shang Gao, M. B. Stone, David Dahlbom, Kipton Barros, Cristian D. Batista, A. D. Christianson
Abstract
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 Ba 2 YRuO 6 and Ba 2 LuRuO 6 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.