Gate-Tunable Quantum Acoustoelectric Transport in Graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Acoustoelectric transport, driven by acoustic waves, is an underexplored area compared to electric and thermoelectric transport.
• Graphene and other 2D materials offer unique electronic properties for novel device applications.

Purpose of the Study:

• To establish a simple, gate-tunable acoustoelectric transport system.
• To investigate acoustoelectric phenomena in graphene-based hybrid nanodevices.
• To explore the potential for magnetic-field-free carrier density extraction and robust quantum oscillation detection.

Main Methods:

• Fabrication of dual-gated acoustoelectric devices using hexagonal boron nitride (hBN)-encapsulated graphene on a lithium niobate (LiNbO3) piezoelectric substrate.
• Generation of longitudinal and transverse acoustoelectric voltages via pulsed surface acoustic waves.
• Application of gate voltages to tune device properties and magnetic fields to induce Landau quantization.

Main Results:

• Successful generation of acoustoelectric voltages in the fabricated devices.
• Demonstration of gate-tunable acoustoelectric signals with profiles similar to Hall resistivity, enabling magnetic-field-free carrier density determination.
• Observation of robust and pronounced acoustoelectric quantum oscillations, exceeding Shubnikov-de Haas oscillations in clarity.

Conclusions:

• A feasible and gate-tunable acoustoelectric transport setup has been demonstrated.
• The method provides a new approach for characterizing carrier density in 2D materials without external magnetic fields.
• The observed quantum oscillations highlight the potential of acoustoelectric transport for exploring quantum phenomena in various van der Waals materials.