Optical signatures of interlayer electron coherence in a bilayer semiconductor

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Physics

Background:

• Atomically thin transition-metal dichalcogenides exhibit novel electronic phenomena.
• Exciton condensation is a sought-after correlated electronic state.
• Understanding interlayer interactions is key to novel quantum states.

Purpose of the Study:

• To investigate experimental signatures of exciton hybridization in MoS2 bilayers.
• To explore the role of interlayer electron coherence in these phenomena.
• To advance the experimental search for exciton condensation.

Main Methods:

• Utilized naturally grown MoS2 homobilayers in a dual-gate device.
• Controlled electron density and out-of-plane electric field independently.
• Observed exciton hybridization under conditions of negligible interlayer electron tunneling.

Main Results:

• Observed unconventional hybridization of interlayer excitons with opposing dipoles.
• Demonstrated that hybridization behavior differs from conventional level crossing/anti-crossing.
• Found hybridization increases with electron density and decreases with temperature, explained by quasi-static random coupling.

Conclusions:

• The observed phenomenon indicates a spatially fluctuating order parameter.
• This suggests interlayer electron coherence, a predicted many-body state.
• Provides experimental evidence towards establishing exciton condensation outside the quantum Hall regime.