Discovery of Anomalous Hall Effect in a New Noncollinear Antiferromagnetic Phase

Unconventional antiferromagnets (AFMs) with spin splitting have garnered significant interest due to their unique characteristics. Conventionally, anomalous Hall effects (AHE) in AFMs are generally observed in both triangular AFM structures and altermagnets. Expanding the AFM structures capable of generating spontaneous AHE is an important direction. In this study, a giant anomalous Hall conductivity (AHC) exceeding 180 S cm^-1 is observed in the M-1 phase of Mn₃GaN. Through electronic transport measurements, it demonstrates that the AHE primarily originates from the new tetragonal AFM structure in the M-1 phase. First-principles calculations show that the AHE arises from a non-zero Berry curvature integration over the Brillouin Zone, which is linked to slight spin canting that breaks time-reversal symmetry. This findings offer a new candidate for unconventional AFMs, and pave the way for the development of topological physics and AFM spintronics.