We characterize the magnetic ground state of the topological kagome metal ${\mathrm{GdV}}_6{\mathrm{Sn}}_6$ via resonant x-ray diffraction. Previous magnetoentropic studies of ${\mathrm{GdV}}_6{\mathrm{Sn}}_6$ suggested the presence of a modulated magnetic order distinct from the ferromagnetism that is easily polarized by the application of a magnetic field. Diffraction data near the Gd-$L_2$ edge directly resolve a $c$-axis modulated spin structure order on the Gd sublattice with an incommensurate wave vector that evolves upon cooling toward a partial lock-in transition. While equal moment (spiral) and amplitude (sine) modulated spin states cannot be unambiguously discerned from the scattering data, the overall phenomenology suggests an amplitude modulated state with moments predominantly oriented in the $ab$ plane. Comparisons to the “double-flat” spiral state observed in Mn-based $R{\mathrm{Mn}}_6{\mathrm{Sn}}_6$ kagome compounds of the same structure type are discussed.

• Received 21 April 2023
• Accepted 26 June 2023

DOI:https://doi.org/10.1103/PhysRevB.108.035134