Planar topological Hall effect from conical spin spirals

Planar Topological Hall effect (PTHE), with an external magnetic field applied in the plane of the charge current, is believed to arise from in-plane skyrmions. Here, we propose that the PTHE can robustly appear also from an unexpected source, the conical spin spiral phase, realizable in a wide variety of materials. We show that for both in-plane skyrmion tubes and conical spin spirals, the PTHE is two-fold symmetric with respect to the magnetic-field angle, while it is four-fold symmetric for labyrinth domains of orthogonal conical spin spirals. We predict that the symmetry and thickness-dependence of the PTHE can distinguish between the two scenarios, unambiguously probing the nature of the antisymmetric spin-exchange interaction and the resulting magnetic texture.