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Bright and Dark Exciton Coherent Coupling and Hybridization Enabled by External Magnetic Fields
Varun Mapara1, Arup Barua1, Volodymyr Turkowski2
1Department of Physics, University of South Florida, Tampa, Florida 33620, United States.
Nano Letters
|February 7, 2022
Summary
Strong magnetic fields control light interactions in WSe2. This research demonstrates magnetic field-induced control over bright and dark excitons, enhancing dephasing times and enabling quantum beating in 2D semiconductors.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Optics
Background:
- Monolayer transition metal dichalcogenides like WSe2 exhibit unique excitonic properties.
- Understanding exciton dynamics is crucial for optoelectronic applications.
Purpose of the Study:
- Investigate the impact of magnetic fields on bright and dark excitons in monolayer WSe2.
- Explore magnetic field control over exciton coherence and dephasing.
Main Methods:
- Magnetic field-dependent optical spectroscopy (up to 25 T).
- Polarization-dependent measurements.
- Broadband femtosecond pulse excitation.
- Time-dependent density functional theory (TD-DFT) calculations.
Main Results:
- Parallel magnetic fields partially brighten lower-energy excitons, increasing dephasing time.
- Simultaneous excitation of bright and partially allowed states leads to quantum beating.
- Perpendicular magnetic fields induce hybridization of bright and dark excitons via energy shifts.
- TD-DFT calculations accurately reproduce experimental observations.
Conclusions:
- Magnetic fields offer a powerful tool to manipulate optical excitations in 2D semiconductors.
- Control over coherent dephasing and coupling is achievable using external magnetic fields.
- These findings pave the way for novel optoelectronic devices based on atomically thin materials.
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