Unconventional Anomalous Hall Effect in Hexagonal Polar Magnet Y ₃ Co ₈ Sn ₄

Abstract A rare realization of unconventional anomalous Hall effect (UAHE) both below and above the magnetic transition temperature ( T C ) in a hexagonal noncentrosymmetric magnet Y 3 Co 8 Sn 4 , using a combined experimental and ab initio calculations. Occurrence of such UAHE is mainly attributed to the reciprocal () topology (i.e., the presence of topological Weyl points at/near the Fermi level), along with some contribution from the topological magnetic texture (at low temperatures), as inferred from the measured field‐dependent ac susceptibility. The effect of UAHE on the measured transport behavior however evolves differently with temperature above and below T C = 53 K, suggesting different physical mechanism responsible in the two phases. A unique planar ferrimagnetic ordering is found to be the most stable state with ab ‐plane as the easy plane below T C . The simulated net magnetization and the moment per Co atom agrees fairly well with the experimentally measured values. A reasonably large anomalous Hall conductivity (AHC) is also observed in both the phases (above and below T C ) of the present compound, which is again not so ubiquitous. The results underscore the family of R 3 Co 8 Sn 4 (R = rare earth) polar magnets as a compelling backdrop for exploring the synergy of magnetism and topological non‐trivial electronic states, pivotal for spintronic applications.