Strong Surface-Enhanced Coherent Phonon Generation in van der Waals Materials
Terahertz (THz) coherent phonons have emerged as promising candidates for the next generation of high-speed, low-energy information carriers in atomically thin phononic or phonon-integrated on-chip devices. However, effectively manipulating THz coherent phonons remains a significant challenge. In this study, we investigated THz coherent phonon generation in exfoliated van der Waals (vdW) flakes of Fe<sub>3</sub>GeTe<sub>2</sub>, Fe<sub>5</sub>GeTe<sub>2</sub>, and FePS<sub>3</sub>. We successfully generated the THz A<sub>1g</sub> coherent phonon mode in these vdW flakes. An innovative approach involved partially exfoliating vdW flakes on a gold substrate and partially on a silicon (Si) substrate to compare the THz coherent phonon generation between both sides. Interestingly, we observed a significantly enhanced THz coherent phonon in the vdW/gold area compared with that in the vdW/Si area. Frequency-domain Raman mapping across the vdW flakes corroborated these findings. Numerical simulations further indicated a stronger enhanced surface field in vdW/gold structures than in vdW/Si structures. Consequently, we attribute the observed enhancement in THz coherent phonon generation to the increased surface field on the gold substrate. This enhancement was consistent across the three different vdW materials studied, suggesting the universality of this strategy. Our results hold promise for advancing the design of THz phononic and phonon-integrated devices.
Authors
- Narayanan Kuthirummal
- Kevin T. Crampton (ORCID: https://orcid.org/0000-0002-1258-7895)
- Apoorva Chaturvedi (ORCID: https://orcid.org/0000-0002-6606-0706)
- Alem Teklu (ORCID: https://orcid.org/0000-0002-1524-2323)
- Alan G. Joly (ORCID: https://orcid.org/0000-0003-2931-4524)
- Hasitha Suriya Arachchige
- David Mandrus (ORCID: https://orcid.org/0000-0003-3616-7104)
- Cheng Gong (ORCID: https://orcid.org/0000-0001-7714-6380)
- Christian Brennan (ORCID: https://orcid.org/0000-0002-5818-5816)
- Brian O'callahan (ORCID: https://orcid.org/0000-0001-9835-3207)
- Chih-Feng Wang (ORCID: https://orcid.org/0000-0002-3085-6614)
- Ti Xie (ORCID: https://orcid.org/0000-0003-2011-5123)
- Ming Hu (ORCID: https://orcid.org/0000-0002-8209-0139)
- Hua Zhang (ORCID: https://orcid.org/0000-0001-9518-740X)
- Leilei Shi (ORCID: https://orcid.org/0000-0002-0980-7500)
- Yu Gong (ORCID: https://orcid.org/0000-0002-9357-9503)
- Qian Zhang (ORCID: https://orcid.org/0000-0001-5975-9781)
Institutions
- Pacific Northwest National Laboratory (US)
- University of South Carolina (US)
- City University of Hong Kong (HK)
- Nanyang Technological University (SG)
- College of Charleston (US)
- Environmental Molecular Sciences Laboratory (US)
- City University of Hong Kong, Shenzhen Research Institute (CN)
- University of Maryland, College Park (US)
- University of Tennessee at Knoxville (US)
Publication Details
- Journal
- The Journal of Physical Chemistry Letters
- Published
- 2024-10-10
- DOI
- https://doi.org/10.1021/acs.jpclett.4c02208
- Citations
- 2
- Primary Topic
- Thermal properties of materials
- Type
- article
- Field-Weighted Citation Impact
- 0.23
Funders
- National Science Foundation
- Gordon and Betty Moore Foundation
- Biological and Environmental Research
- Workforce Development for Teachers and Scientists
- Chemical Sciences, Geosciences, and Biosciences Division
- Air Force Office of Scientific Research