Capacitively and Inductively Coupled Excitons in Bilayer MoS_{2}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Two-dimensional (2D) semiconductors like MoS2 exhibit unique excitonic properties.
• Understanding exciton coupling is crucial for developing novel optoelectronic devices.
• Homobilayer MoS2 provides a platform to study interlayer and intralayer exciton interactions.

Purpose of the Study:

• To investigate the coupling mechanisms between intralayer A/B excitons and interlayer excitons (IE) in MoS2 homobilayers.
• To determine the magnitude and phase of coupling constants using optical susceptibility measurements.
• To realize a tunable lowest-energy momentum-direct exciton.

Main Methods:

• Optical susceptibility measurements to probe exciton coupling.
• Theoretical interpretation of coupling mechanisms as hole tunneling and electron-hole exchange.
• Utilizing interlayer excitons as a sensor for intravalley exchange coupling.

Main Results:

• Identified a 0-phase (capacitive) coupling between IE and B excitons.
• Identified a π-phase (inductive) coupling between IE and A excitons.
• Demonstrated that A and B excitons possess mixed spin states even in a monolayer.
• Achieved a bright, tunable lowest-energy momentum-direct exciton under high electric fields.

Conclusions:

• The study elucidates the distinct coupling mechanisms governing exciton interactions in MoS2.
• These findings provide insights into spin mixing in excitons and enable precise control over exciton properties.
• The realization of a tunable exciton opens avenues for advanced quantum information processing and optoelectronics.