Electrically Sign-Reversible Topological Hall Effect in a Top-Gated Topological Insulator (Bi,Sb)2Te3 on a Ferrimagnetic Insulator Europium Iron Garnet

TL;DR

This study demonstrates a large, electrically reversible sign change in the topological Hall effect in a top-gated topological insulator on a ferrimagnetic insulator, linked to skyrmions and tunable via Fermi level adjustments.

Contribution

It reveals the sign-reversible topological Hall effect in a topological insulator heterostructure, advancing understanding of skyrmion-driven phenomena and enabling potential spintronics applications.

Findings

Large THE (~10 ohm) observed at 2 K

THE sign reverses with Fermi level tuning

Consistent with skyrmion-driven mechanisms

Abstract

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. However, the intriguing interplay between the topological surface state and THE is yet to be fully understood. In this work, we report a large THE of ~10 ohm (~4 micro-ohm*cm) at 2 K with an electrically reversible sign in a top-gated 4 nm TI (Bi0.3Sb0.7)2Te3 (BST) grown on a ferrimagnetic insulator (FI) europium iron garnet (EuIG). Temperature, external magnetic field angle, and top gate bias dependences of magnetotransport properties were investigated and consistent with a skyrmion-driven THE. Most importantly, a sign change in THE was discovered as the Fermi level was tuned from the upper to the lower parts of the gapped Dirac cone and vice versa. This discovery is anticipated to impact technological applications in ultralow power skyrmion-based spintronics.