Chiral Anomaly and Anomalous Hall Effect in parent and Fe doped Hexagonal-Mn3+δGe Weyl semimetals

Topological quantum materials have attracted enormous attention since their discovery due to the observed anomalous transport properties, which originate from the non-zero Berry curvature. Mn3+δGe has gained special attention because of its large anomalous transport effects that persist starting from Néel temperature (365 K) down to 2 K. Due to the presence of very small in-plane ferromagnetic component, chirality of magnetic structure can be controlled easily by applying just a few hundred Oersted (Oe) of magnetic field. Hexagonal - Mn3+δGe stabilizes in the range of δ = 0.2 – 0.55. In order to understand the involved quantum phenomena - Anomalous Hall effect (AHE) - in such materials, it is also important to check the stability of AHE with the variation of δ. Due to specific mirror symmetry of the triangular antiferromagnetic structure, AHE is expected to be observed when magnetic field (B) is applied along x or y crystallographic axis. AHE has been reported in the lower range of δ (= 0.22, 0.32 [Kiyohara et al. (2015)]), however the upper range of δ was still unexplored. We have investigated samples with the upper range of δ (~ 0.55) and AHE with very small Hall - hysteresis (