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Strong Surface-Enhanced Coherent Phonon Generation in van der Waals Materials
Christian Brennan1, Alan G Joly2, Chih-Feng Wang2
1Department of Physics and Astronomy, College of Charleston, 58 Coming Street, Charleston, South Carolina 29424, United States.
The Journal of Physical Chemistry Letters
|October 10, 2024
Summary
Researchers enhanced terahertz (THz) coherent phonon generation in van der Waals materials by using a gold substrate. This strategy boosts signal strength for future high-speed, low-energy electronic devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Terahertz (THz) coherent phonons are key for next-generation high-speed, low-energy information processing in on-chip devices.
- Efficient manipulation of THz coherent phonons is crucial but remains a significant challenge for device applications.
Purpose of the Study:
- To investigate THz coherent phonon generation in exfoliated van der Waals (vdW) flakes of Fe3GeTe2, Fe5GeTe2, and FePS3.
- To explore a novel method for enhancing THz coherent phonon generation using different substrates.
Main Methods:
- Exfoliation of vdW flakes (Fe3GeTe2, Fe5GeTe2, FePS3) onto a substrate with alternating gold and silicon (Si) areas.
- Generation and detection of THz coherent phonons, specifically the A1g mode.
- Frequency-domain Raman mapping and numerical simulations to analyze surface fields.
Main Results:
- Successfully generated the THz A1g coherent phonon mode in the studied vdW flakes.
- Observed significantly enhanced THz coherent phonon generation in vdW flakes on gold compared to those on Si.
- Numerical simulations confirmed a stronger enhanced surface field in vdW/gold structures, explaining the phonon enhancement.
Conclusions:
- The enhanced surface field on a gold substrate effectively boosts THz coherent phonon generation in vdW materials.
- This substrate engineering strategy is universal across different vdW materials (Fe3GeTe2, Fe5GeTe2, FePS3).
- The findings offer a promising pathway for designing advanced THz phononic and phonon-integrated devices.
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