Gate-Tunable Anomalous Hall Effect in a 3D Topological Insulator/2D Magnet van der Waals Heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Topological insulators (TIs) possess unique surface states with potential for advanced electronic applications.
• Controlling these surface states, particularly through proximity effects with magnetic materials, is crucial for harnessing their properties.

Purpose of the Study:

• To investigate the control of topological surface states in a 3D TI using mechanically stacked van der Waals heterostructures.
• To explore the interaction between a TI and an adjacent magnetic layer for tunable electronic properties.

Main Methods:

• Fabrication of van der Waals heterostructures by mechanically stacking exfoliated flakes of BiSbTeSe2 (TI) and Cr2Ge2Te6 (magnet).
• Characterization of the heterostructures, including measurements of the anomalous Hall effect (AHE).
• Application of gate voltage to tune the AHE amplitude.

Main Results:

• Demonstrated pristine interfaces in TI-magnet bilayers, avoiding interdiffusion issues common in other fabrication methods.
• Observed anomalous Hall effect (AHE) with abrupt hysteretic switching, indicating magnetic control.
• Achieved gate-voltage tunability of the AHE amplitude in a TI-ferromagnet system for the first time, with a peak near the Dirac point.

Conclusions:

• Mechanically stacked van der Waals heterostructures offer an effective route for controlling TI surface states via magnetic proximity effects.
• The observed gate-tunable AHE provides direct evidence of Berry curvature modulation due to exchange interactions at the TI surface.
• This work paves the way for novel spintronic devices based on engineered topological heterostructures.