Establishing magneto-structural relationships in the solid solutions of the skyrmion hosting family of materials: GaV(4)S(8−y)Se(y)

The GaV(4)S(8−y)Se(y) (y = 0 to 8) family of materials have been synthesized in both polycrystalline and single crystal form, and their structural and magnetic properties thoroughly investigated. Each of these materials crystallizes in the F[Formula: see text] [Formula: see text] 3m space group at ambient temperature. However, in contrast to the end members GaV(4)S(8) and GaV(4)Se(8), that undergo a structural transition to the R3m space group at 42 and 41 K respectively, the solid solutions (y = 1 to 7) retain cubic symmetry down to 1.5 K. In zero applied field the end members of the family order ferromagnetically at 13 K (GaV(4)S(8)) and 18 K (GaV(4)Se(8)), while the intermediate compounds exhibit a spin-glass-like ground state. We demonstrate that the magnetic structure of GaV(4)S(8) shows localization of spins on the V cations, indicating that a charge ordering mechanism drives the structural phase transition. We conclude that the observation of both structural and ferromagnetic transitions in the end members of the series in zero field is a prerequisite for the stabilization of a skyrmion phase, and discuss how the absence of these transitions in the y = 1 to 7 materials can be explained by their structural properties.