The Double-Q Ground State with Topological Charge Stripes in the Skyrmion Candidate GdRu2Si2

GdRu_2Si_2 is a centrosymmetric magnet in which a skyrmion lattice has recently been discovered. Here, we investigate the magnetic structure of the zero field ground state using neutron diffraction on single crystal and polycrystalline ^160GdRu_2Si_2. In addition to observing the principal propagation vectors 𝐪_1 and 𝐪_2, we discover higher order magnetic satellites, notably 𝐪_1 + 2𝐪_2. The appearance of these satellites are explained within the framework of a new double-Q constant-moment solution. Using powder diffraction we implement a quantitative refinement of this model. This structure, which contains vortexlike motifs, is shown to have a one-dimensional topological charge density.