Dynamically tunable moiré exciton Rydberg states in a monolayer semiconductor on twisted bilayer graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Moiré excitons are optical excitations in 2D semiconductors with moiré superlattices.
• Existing platforms lack dynamic tunability of moiré potentials to control exciton properties.

Purpose of the Study:

• To develop a continuously tunable moiré potential in monolayer WSe2.
• To engineer moiré excitons and explore their interactions with twisted bilayer graphene (TBG).

Main Methods:

• Utilizing the proximity of monolayer WSe2 to twisted bilayer graphene (TBG) near the magic angle.
• Employing electrostatic gating to tune the local charge density and dielectric superlattice potential.
• Observing and analyzing moiré exciton Rydberg branches and their energy splitting.

Main Results:

• Demonstrated a tunable moiré potential in monolayer WSe2 via gating of nearby TBG.
• Observed emergent moiré exciton Rydberg branches with altered energy splitting due to hybridization.
• Showcased the ability of these Rydberg states to probe strongly correlated electronic states in TBG.

Conclusions:

• Introduced a novel platform for engineering moiré excitons with dynamic control.
• Provided optical access to study electronic states with small correlation gaps in TBG.
• Opened new avenues for investigating exciton-electron interactions in moiré systems.