First-principles calculations of noncollinear magnetization densities in quantum spin liquid candidate materials

Neutron scattering has proven successful at observing signatures of quantum spin liquids (QSLs) including fractionalized excitations, however, accurate magnetic form factors are needed to analyze the data. These are commonly treated in an isolated, isotropic ion approximation. But the local magnetic degrees of freedom in QSL candidate materials are j_eff=1/2 moments which are anisotropic [1], hybridize with nearby anions, and, as we show, exhibit intra-atomic noncollinearity in the magnetization density. These features are liable to notably affect neutron scattering measurements and move beyond the basic magnetic form factor. We propose specific scattering directions for neutron experiments to maximally detect the unique quality of the magnetization density in these materials.



[1] Colin L. Sarkis et al, Phys. Rev. B 109, 104432 (2024).