Room temperature observation of the anomalous in-plane Hall effect in a Weyl ferromagnet.

Topologically nontrivial electronic states can lead to novel anomalous Hall effects, with room temperature manifestations promising for applications in magnetic sensing, spintronics, and energy harvesting. The anomalous in-plane Hall effect is expected in topological magnetic materials under an in-plane magnetic field, but its detection has been challenging because of strict symmetry requirements. Here, we combine molecular beam epitaxy of the kagome metal Fe3Sn, electric Hall effect measurements, and theoretical calculations to propose and demonstrate that the kagome lattice motif combined with spin-orbit coupling and canted ferromagnetism induces the anomalous in-plane Hall effect at room temperature via topological Weyl points. Additionally, we synthesize a topological thin-film heterostructure with Fe3Sn and ferromagnetic CoFeB, showing enhanced anomalous in-plane Hall effect amplitude due to CoFeB's magnetic stray field. This work establishes a design framework for topological magnets and heterostructures aimed at discovering and controlling anomalous Hall effects for technological applications.