Extrinsic suppression of the anomalous Hall effect in the Fe-rich kagome magnet Fe3Sn

In Fe-based kagome magnets, Fe3Sn has been predicted to have the largest intrinsic anomalous Hall conductivity (AHC) and the highest Curie temperature, TC = 743 K. However, the current experimental results show that the total AHC is much lower than the predicted value due to the strong extrinsic contribution. To suppress the extrinsic contribution and thus enhance AHC, we increased the Fe content in the stoichiometric Fe3Sn. We found that the extrinsic contribution is significantly suppressed, and the intrinsic contribution is dominant and approaches the theoretically predicted value of 555 S/cm for polycrystals over the entire temperature range. The scaling relationship shows that the skew scattering mainly provides the extrinsic contribution and compensates with intrinsic contribution. Based on the formula for the skew scattering, we analyzed why the skew scattering was suppressed and found that the spin-orbit coupling strength provided by the impurity center was the key. The spin-orbit coupling strength provided by Fe as an impurity center in this study is much smaller than that of Sn as an impurity center in previous studies. Therefore, the AHC in Fe-rich Fe3Sn obeys the unified theory, while the AHC in Sn-rich Fe3Sn deviates from the unified theory. Our study provides a promising solution for regulating the extrinsic contribution to the anomalous Hall effect in kagome magnets.