Unusual multiple magnetic transitions and anomalous Hall effect observed in antiferromagnetic Weyl semimetal, Mn2.94Ge (Ge-rich)

Abstract

Abstract We report on the magnetic and Hall effect measurements of the magnetic Weyl semimetal, Mn2.94Ge (Ge-rich) single crystal. From the magnetic properties study, we identify unusual multiple magnetic transitions below the N e ˊ el temperature of 353 K, such as the spin-reorientation (T SR) and ferromagnetic-like transitions. Consistent with the magnetic properties, the Hall effect study shows unusual behavior around the spin-reorientation transition. Specifically, the anomalous Hall conductivity increases with increasing temperature, reaching a maximum at T SR, which then gradually decreases with increasing temperature. This observation is quite in contrast to the Mn 3 + δ Ge (Mn-rich) system, though both compositions share the same hexagonal crystal symmetry. This study unravels the sensitivity of magnetic and topological properties on the Mn concentration.