Emergent Giant Topological Hall Effect at the van der Waals Ferromagnet/Topological Insulator Interface

Two-dimensional (2D) van der Waals (vdW) magnet-based heterostructures provide a vital platform for manipulating magnetic ground states and hosting complex spin textures. The topological Hall effect (THE) is a powerful tool for probing these textures in such systems. However, achieving a sizable THE in 2D vdW ferromagnets remains challenging due to the absence of broken inversion symmetry and sufficiently strong spin–orbit coupling (SOC). Here, we report an emergent giant topological Hall resistivity of 6.9 μΩ·cm at 10 K by interfacing the 2D ferromagnet Fe3GeTe2 (FGT) with the topological insulator BiSbTeSe2 (BSTS). Systematic temperature- and thickness-dependent studies suggest the origin of this pronounced signal to be the interfacial Dzyaloshinskii–Moriya interaction (DMI). Furthermore, temperature-field mapping reveals the coexistence of two distinct phases that we identify as having opposite topological charge. Our results establish these vdW ferromagnet/topological insulator heterostructures as a robust platform for enhanced interfacial THE, opening new avenues for high-efficiency topological spintronics.