Tunable band-filling effects on thermoelectric properties and anomalous Hall conductivity in Weyl semimetal Co3Sn2 S2

The magnetic Weyl semimetal Co3Sn2S2 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 Co3Sn2S2. The temperature-dependent Seebeck coefficient (S) implies that the reduction of the band gap and the shift in the Fermi level (EF) 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 (σxyA). Specifically, Fe substitution increases σxyA via skew scattering, while Ni substitution increases σxyA 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 Co3Sn2S2 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 Co3Sn2S2. These findings provide deeper insight into the band-filling effects on both TE and anomalous Hall transport in Co3Sn2S2, offering perspectives for topological spintronics and TE applications.