Abstract
The topological Hall effect (THE), an electrical transport signature of systems with chiral spin textures like
skyrmions, has been observed recently in topological insulator (TI)-based magnetic heterostructures. The
strong spin-orbit coupling and the broken spatial inversion symmetry in such heterostructures could lead to
a sizable interfacial Dzyaloshinsky-Moriya interaction, favorable for skyrmion formation and pronounced
THE. However, the intriguing interplay between the topological surface state (TSS) and THE is yet to be fully
understood. In thiswork, we report an unprecedentedly large THE signal of ∼10 (∼4 μ cm at 2 K) with an
electrically reversiblesign in a top-gated 4 nm TI (Bi0.3Sb0.7 )2Te3 (BST) grown on a ferrimagnetic insulator
(FI) europium iron garnet(EuIG). The dependence of THE on temperature, external magnetic field angle, and
gate bias was investigated and is consistent with the prediction of a skyrmion-driven THE, amenable to
elucidate the origin of THE that occurred in TI-based heterostructures. Moreover, a sign change in THE was
discovered as the Fermi level was tuned electrically from the upper (electron-doped region) to the lower
parts (hole-doped region) of the gapped BST Dirac cone and vice versa. We show that the exploitation of
the TSS features has led to a sign-reversal of THE repeatedly in a TI/FI top-gate stack. This discovery may
impact technological applications in ultralow power skyrmion-based spintronics.