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Exciton-coupled coherent magnons in a 2D semiconductor
Youn Jue Bae1, Jue Wang1, Allen Scheie2
1Department of Chemistry, Columbia University, New York, NY, USA.
Nature
|September 7, 2022
Summary
Researchers observed strong coupling between magnons and excitons in 2D magnetic semiconductor CrSBr. This allows coherent magnons to travel long distances, enabling new possibilities for spintronics and quantum technologies.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Information Science
Background:
- Two-dimensional (2D) magnets and van der Waals heterostructures offer novel physical phenomena.
- 2D magnetic semiconductors, like CrSBr, combine magnetic and semiconducting properties, enabling exciton-magnon coupling.
- Coherent magnons are promising for energy-efficient information transfer in spintronics and quantum systems.
Purpose of the Study:
- To investigate and demonstrate strong magnon-exciton coupling in the 2D antiferromagnetic semiconductor CrSBr.
- To explore the potential of optically accessing and controlling spin information via coherent magnons.
- To characterize the propagation distance and coherence time of these coupled magnons.
Main Methods:
- Utilizing above-gap optical excitation to launch coherent magnons in CrSBr.
- Employing time-resolved exciton sensing to detect and track magnon propagation.
- Investigating magnon-exciton coupling across various layer numbers and magnetic configurations.
Main Results:
- Demonstrated strong coupling between coherent magnons and excitons in 2D CrSBr.
- Observed coherent magnons traveling over seven micrometres with a coherence time exceeding five nanoseconds.
- Confirmed the presence of these coupled magnons in samples down to the bilayer limit, irrespective of layer parity or magnetization compensation.
Conclusions:
- The strong magnon-exciton coupling in 2D CrSBr provides an efficient optical pathway to manipulate spin information.
- These long-lived, coherent magnons are suitable for applications in optically accessible spintronics and magnonics.
- The findings pave the way for utilizing 2D magnetic semiconductors in advanced quantum interconnects and information processing.
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