Tunable band-filling effects on thermoelectric properties and anomalous Hall conductivity in Weyl semimetal Co 3 Sn 2 S 2

The magnetic Weyl semimetal Co 3 Sn 2 S 2 has garnered significant experimental and theoretical interest, particularly regarding its electronic structure and transport properties. In this study, we comprehensively investigated the effects of Fe and Ni substitution in Co 3 Sn 2 S 2 . The temperature-dependent Seebeck coefficient ( S ) implies that the reduction of the band gap and the shift in the Fermi level ( E F ) due to Fe and Ni substitution, which was supported by angle-resolved photoemission spectroscopy results. These band-structure modifications influence not only thermoelectric (TE) performance but also the anomalous Hall conductivity ( σ xy A ). Specifically, Fe substitution increases σ xy A via skew scattering, while Ni substitution increases σ xy A via intrinsic deflection with minor skew scattering. Additionally, the Fe and Ni dopant-induced changes in the c / a ratio were demonstrated using high-resolution powder synchrotron x-ray diffraction, which explains the different modulation in the magnetic anisotropy of Co 3 Sn 2 S 2 due to the magnetostriction effect. Notably, the oxidation states of Co, Fe, and Ni in each single crystal were confirmed as 0 using x-ray absorption near-edge structure analysis, further explaining the dopant-induced suppression in ferromagnetism of Co 3 Sn 2 S 2 . These findings provide deeper insight into the band-filling effects on both TE and anomalous Hall transport in Co 3 Sn 2 S 2 , offering perspectives for topological spintronics and TE applications.