Pressure-Driven Moiré Potential Enhancement and Tertiary Gap Opening in Graphene/h-BN Heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Engineering

Background:

• Moiré superlattices offer tunable potentials for quantum states, but dynamic control of potential strength is difficult.
• Existing methods for modulating moiré potentials are limited, hindering exploration of correlated quantum phenomena.

Purpose of the Study:

• To develop a high-pressure quantum transport technique for van der Waals heterostructures.
• To investigate the effect of hydrostatic pressure on moiré superlattices, specifically in graphene/hexagonal boron nitride (h-BN).
• To explore the potential of pressure as a parameter for engineering correlated quantum states.

Main Methods:

• Development of a high-pressure quantum transport technique reaching approximately 9 GPa.
• Utilizing encapsulated moiré devices for precise measurements.
• Analyzing changes in valence bandwidth and band gaps under applied pressure.

Main Results:

• Demonstrated substantial enhancement of moiré potential strength in aligned graphene/h-BN under pressure.
• Observed suppression of the first valence bandwidth and near-doubling of the primary band gap.
• Reported the first observation of a tertiary band gap emerging above 6.4 GPa, confirming theoretical predictions.

Conclusions:

• Hydrostatic pressure is established as a universal parameter for reshaping moiré band structures.
• The developed technique expands the accessible pressure regimes for quantum transport studies.
• This work opens new avenues for exploring correlated quantum phases in moiré systems.