Interplay of Structural Modulation and Magnetism in FeGe_1-xSb_x

Recent studies on FeGe_1-xSb_x (0 < x < 0.2) show that Sb doping induces structural modulations that affect the magnetic response. Superlattice peaks emerge once Sb doping exceeds 12%, consistent with the formation of a structural supercell. This doping substantially modifies the magnetic properties relative to pristine FeGe. As suggested by susceptibility, the x = 0.12 composition exhibits a pronounced jump at 200 K, typically associated with a spin-reorientation transition. Despite displaying a similar crystallographic framework and superlattice modulation, our measurement of the x = 0.15 sample shows no clear evidence of an anomaly associated with spin reorientation, possibly suggesting a distinct magnetic structure. These observations indicate that while Sb substitution drives a common structural modulation, different doping levels stabilize distinct atomic structure and magnetization behavior. Besides comprehensive transport measurements, we also provide single-crystal neutron scattering data across doping ratios to clarify the structure–magnetism interplay.