Tuning the anomalous Nernst and Hall effects with shifting the chemical potential in Fe-doped and Ni-doped Co₃Sn₂S₂

Abstract

Co$_3$Sn$_2$S$_2$ is believed to be a magnetic Weyl semimetal. It displays large anomalous Hall, Nernst and thermal Hall effects with a remarkably large anomalous Hall angle. Here, we present a comprehensive study of how substituting Co by Fe or Ni affects the electrical and thermoelectric transport. We find that doping alters the amplitude of the anomalous transverse coefficients. The maximum decrease in the amplitude of the low-temperature anomalous Hall conductivity $\sigma^A_{ij}$ is twofold. Comparing our results with theoretical calculations of the Berry spectrum assuming a rigid shift of the Fermi level, we find that given the modest shift in the position of the chemical potential induced by doping, the experimentally observed variation occurs five times faster than expected. Doping affects the amplitude and the sign of the anomalous Nernst coefficient. Despite these drastic changes, the amplitude of the $\alpha^A_{ij}/\sigma^A_{ij}$ ratio at the Curie temperature remains close to $\approx 0.5 k_B/e$, in agreement with the scaling relationship observed across many topological magnets.

How to Enhance Anomalous Hall Effects in Magnetic Weyl Semimetal Co3Sn2S2?

“…For Co 3 Sn 2 S 2 , a wide variation of experimental σ xy A is reported in the literature (486–1372 Ω –1 cm –1 , ,− ,,,,,− ,,− see Table S4), which cannot be comprehended on the basis of the present understanding. Such large variation in AHC cannot be attributed to deviation in the magnetic field direction from the c axis (deviation in AHC ∼ 1%) or error in sample dimensions measurement (deviation in AHC ∼ 12.2%).…”