Noncoplanar magnetic state and scalar spin chirality driven large anomalous Hall effects in electron doped Mn₃Sn

The discovery of a large anomalous Hall effect (AHE) in non-collinear antiferromagnet Mn₃Sn begins a new era of antiferromagnetic (AFM) spintronics [Nakatsuji et al., Nature 527, 212 (2015]. Mn₃Sn exhibits an in-plane triangular 120 degree AFM ordering owing to the geometrical frustration in the kagome lattice. In this work, we present a combined theoretical and experimental investigation to show how suitable electron doping in the Mn₃Sn can drastically change the in-plane AFM structure to a tunable non-coplanar magnetic state. We demonstrate that the higher-order exchange interaction in the magnetic Hamiltonian drives the planar magnetic state to the non-coplanar one. We also find a large scalar spin chirality (SSC)-induced topological AHE, whose size is closely correlated with the system's degree of noncoplanarity. Additionally, a unique simultaneous manipulation of the dual order in the system is demonstrated, where the Hall signal due to in-plane AFM order can be switched independently without perturbing the SSC-induced signal. The current work provides a new avenue for investigating unique quantum phenomena in triangular AFM materials where higher order magnetic interactions play a vital role.