Angular dependence of the topological Hall effect in the uniaxial van der Waals ferromagnet Fe3GeTe2

Fe3GeTe2 is a paradigmatic two-dimensional ferromagnet with strong uniaxial anisotropy. In this work we systematically studied the angular dependence of electrical transport properties in Fe3GeTe2 single crystals, and uncovered an unexpected topological Hall effect (THE) in the configuration of large tilted magnetic fields. The Hall resistivity and magnetoresistance varied periodically when the external magnetic field rotated in the ac (or bc) plane, while the THE emerged and maintained robust with fields swept across the nearby hard-magnetized ab plane. The approximate in-plane THE covered the whole temperature region below T-C(similar to 150 K) and reached the maximum value at 100 K. Emergence of an internal gauge field was proposed to explain the origin of this large THE, which is generated by either the possible topological domain structure of uniaxial Fe3GeTe2 or the noncoplanar spin structure forming during the in-plane magnetization. Our results promise to provide an alternative detection method to the in-plane skyrmion formation and may bring a brand new prospective to magnetotransport studies in condensed matter physics.