Magnetization induced in-plane Anomalous Hall effect in a topological semimetal coupled with a ferromagnet

Anomalous Hall Effect (AHE) typically refers to a large change in Hall resistance associated with out-of-plane magnetization, requiring a lack of mirror symmetry along the z-axis in relation to the electric measurement setup (R_yx = V_y/I_x). Since magnetization or an external magnetic field only breaks mirror symmetries along the direction it is aligned with, Hall effects are typically observed when the magnetization or field is oriented along the z-axis. In conventional materials with multiple mirror symmetries along the z-axis, in-plane magnetization cannot fully break the symmetry needed to induce AHE. However, in magnetic systems with only one or no mirror symmetry along z, an in-plane AHE can occur. For example, in a system with only yz mirror symmetry, AHE is allowed when the magnetization is aligned with the y-axis, as this breaks the remaining symmetry. In our experiments, by combining a low-symmetry topological semimetal, which has strong spin-orbit coupling, with a van der Waals ferromagnet, we create a heterostructure with only bc mirror symmetry. In these heterostructures, we realize both in-plane and out-of-plane AHE, consistent with symmetry requirements, which we will discuss in detail.