Gate-tunable Intrinsic Anomalous Hall Effect in Epitaxial MnBi2Te4 Films

TL;DR

This study demonstrates gate-tunable intrinsic anomalous Hall effect in MnBi2Te4 thin films, revealing the interplay of Berry curvature, magnetism, and band structure, with potential for electronic device applications.

Contribution

It uncovers the gate-controlled sign reversal of AHE in MnBi2Te4 films and explains the mechanism via Berry curvature competition through first-principles calculations.

Findings

Intrinsic AHE dominated by Berry curvature in MnBi2Te4 films.

Gate voltage induces ambipolar conduction and n-p transition.

Sign reversal of AHE observed in thinner MnBi2Te4 under gating.

Abstract

Anomalous Hall effect (AHE) is an important transport signature revealing topological properties of magnetic materials and their spin textures. Recently, antiferromagnetic MnBi2Te4 has been demonstrated to be an intrinsic magnetic topological insulator that exhibits quantum AHE in exfoliated nanoflakes. However, its complicated AHE behaviors may offer an opportunity for the unexplored correlation between magnetism and band structure. Here, we show the Berry curvature dominated intrinsic AHE in wafer-scale MnBi2Te4 thin films. By utilizing a high-dielectric SrTiO3 as the back-gate, we unveil an ambipolar conduction and electron-hole carrier (n-p) transition in ~7 septuple layer MnBi2Te4. A quadratic relation between the saturated AHE resistance and longitudinal resistance suggests its intrinsic AHE mechanism. For ~3 septuple layer MnBi2Te4, however, the AHE reverses its sign from pristine negative to positive under the electric-gating. The first-principles calculations demonstrate that such behavior is due to the competing Berry curvature between polarized spin-minority-dominated surface states and spin-majority-dominated inner-bands. Our results shed light on the physical mechanism of the gate-tunable intrinsic AHE in MnBi2Te4 thin films and provide a feasible approach to engineering its AHE.