Giant anomalous Hall effect from spin-chirality scattering in a chiral magnet

Topological spin textures give rise to various emergent phenomena, which originate from the interplay between scalar-spin chirality and conduction electrons. In that sense, a spin hedgehog lattice in MnGe provides one distinct example, where the dense emergent magnetic field (~ 40 T) and its fluctuations lead to novel electrodynamics.
We report the observation of giant anomalous Hall effect (AHE) in MnGe thin films. The Hall conductivity and the Hall angle simultaneously reach Ω^-1cm^-1 and , respectively, which are an order of magnitude larger than the typical ferromagnets. The exceptionally large value of σ_xy as well as its transport life-time dependence (σ_xy∝σ_xx) suggest that the AHE is induced by some electron scattering mechanism which is beyond the conventional paradigm. We demonstrate the whole picture of this unusual AHE by showing its temperature, magnetic field, mobility, and film-thickness dependences. The possible origins will also be discussed, especially in terms of a novel skew scattering mechanism arising from the fluctuation-induced scalar-spin chirality.