Weyl points and anomalous transport effects tuned by the Fe doping in Mn3Ge Weyl semimetal

Abstract

The discovery of a significantly large anomalous Hall effect in the chiral antiferromagnetic system—Mn _3 Ge—indicates that the Weyl points are widely separated in phase space and positioned near the Fermi surface. In order to examine the effects of Fe substitution in Mn _3 Ge on the presence and location of the Weyl points, we synthesized (Mn $_{1-\alpha}$ Fe $_{\alpha})_3$ Ge ( $\alpha = 0-0.30$ ) compounds. The AHE was observed in compounds up to α = 0.22, but only within the temperature range where the magnetic structure remains the same as the Mn _3 Ge. Additionally, positive longitudinal magnetoconductance and planar Hall effect (PHE) were detected within the same temperature and doping range. These findings strongly suggest the existence of Weyl points in (Mn $_{1-\alpha}$ Fe $_{\alpha})_3$ Ge ( $\alpha = 0-0.22$ ) compounds. Further, we observed that with an increase in Fe doping fraction, there is a significant reduction in the magnitude of anomalous Hall conductivity, PHE, and positive longitudinal magnetoconductance, indicating that the Weyl points move further away from the Fermi surface. Consequently, it can be concluded that suitable dopants in the parent Weyl semimetals have the potential to tune the properties of Weyl points and the resulting anomalous electrical transport effects.

Keywords

• Weyl semimetal
• antiferromagnet
• planer Hall effect
• anomalous Hall effect
• doping