Incommensurate Magnetic Order in the $\mathbb{Z}_2$ Kagome Metal GdV$_6$Sn$_6$

TL;DR

This study reveals an incommensurate, amplitude-modulated magnetic order in the topological kagome metal GdV$_6$Sn$_6$, characterized by resonant X-ray diffraction, showing a complex magnetic structure that evolves with temperature.

Contribution

First direct characterization of the incommensurate magnetic order in GdV$_6$Sn$_6$ using resonant X-ray diffraction, revealing a modulated spin structure on the Gd sublattice.

Findings

Identified a c-axis modulated spin structure with incommensurate wave vector.

Observed evolution of magnetic order upon cooling towards a lock-in transition.

Suggested an amplitude modulated state with moments mainly in the ab-plane.

Abstract

We characterize the magnetic ground state of the topological kagome metal GdV$_6$Sn$_6$ via resonant X-ray diffraction. Previous magnetoentropic studies of GdV$_6$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 can not 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 $R$Mn$_6$Sn$_6$ kagome compounds of the same structure type are discussed.