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Updated: May 22, 2025
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Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection
Published on: October 13, 2017
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Diffusion of Valley-Coherent Dark Excitons in a Large-Angle Incommensurate Moiré Homobilayer
Arnab Barman Ray1, Trevor Ollis2, K R Sethuraj1,3
1The Institute of Optics, University of Rochester, 480 Intercampus Dr, Rochester, New York 14627, United States.
Nano Letters
|March 14, 2025
Summary
Researchers discovered a unique "mixed" dark exciton in twisted molybdenum diselenide bilayers. This exciton exhibits efficient diffusion and robust valley coherence, paving the way for novel valleytronic devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Optics
Background:
- Twistronics in transition metal dichalcogenides reveals phenomena in small-angle twisted bilayers.
- Large-angle, incommensurate bilayers remain less explored due to broken periodicity.
Purpose of the Study:
- Investigate the physics of large-angle twisted bilayers in molybdenum diselenide.
- Demonstrate novel excitonic behavior and its potential applications.
Main Methods:
- Fabrication of n-doped molybdenum diselenide homobilayers with large twist angles.
- Photoluminescence spectroscopy and temperature-dependent measurements.
- Analysis of exciton diffusion and valley coherence.
Main Results:
- Observation of a brightened dark intralayer exciton in a twisted molybdenum diselenide homobilayer.
- This exciton shows efficient diffusion with lengths exceeding 4 μm.
- Evidence of a brightened dark trion and robust valley coherence.
Conclusions:
- The observed phenomena are attributed to spin-resolved conduction band mixing due to symmetry breaking and dielectric contrast.
- These findings introduce valley-robust
- mixed
- dark excitons.
- Opens new avenues for developing advanced valleytronic devices.
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