  The planar topological Hall effect (PTHE), appeared when the magnetic field
tended to be along the current, is believed to result from the real-space Berry
curvature of the spin spiral structure and has been experimentally observed in
skyrmion-hosting materials. In this paper, we report an experimental
observation of the PTHE in a hexagonal ferromagnetic Fe5Sn3 single crystal.
With a current along the c axis of Fe5Sn3, the transverse resistivity curves
exhibited obvious peaks near the saturation field as the magnetic field rotated
to the current and appeared more obvious with increasing temperature, which was
related to the noncoplanar spin structure in Fe5Sn3. This spin structure
induced nonzero scalar spin chirality, which acted as fictitious magnetic
fields to conduction electrons and contributed the additional transverse
signal. These findings deepen the understanding of the interaction between
conduction electrons and complex magnetic structures and are instructive for
the design of next-generation spintronic devices.
