Dynamically Tunable Hydrodynamic Transport in Boron-Nitride-Encapsulated Graphene

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Graphene encapsulated in hexagonal boron nitride (hBN) offers high-quality channels for studying electronic viscosity.
• Current fabrication methods limit tunability between impurity-dominated and viscous transport in graphene devices.

Purpose of the Study:

• To demonstrate dynamic modulation of charge hydrodynamics in graphene.
• To achieve reversible tuning of disorder levels within a single device.
• To explore the departure from the Wiedemann-Franz law under varying disorder conditions.

Main Methods:

• Utilized ultraviolet (UV) radiation and gate electric fields to dynamically alter charge carrier behavior.
• Created transient trap states in hBN dielectrics using UV light to tune disorder.
• Quantified changes in thermal and electrical transport to assess deviations from the Wiedemann-Franz law.

Main Results:

• Achieved continuous and reversible tuning of disorder levels in monolayer graphene devices at room temperature.
• Observed a significant increase in momentum-relaxing scattering with increasing disorder.
• Demonstrated a near tenfold increase in the Lorentz number, approaching Wiedemann-Franz law restoration in highly disordered graphene.

Conclusions:

• UV radiation provides a potent strategy for dynamically controlling charge hydrodynamics in graphene.
• This method allows for in-situ tuning of transport regimes, bridging impurity-dominated and viscous flow.
• The findings enable new avenues for exploring fundamental electron transport phenomena in advanced materials.