Terahertz phonon engineering with van der Waals heterostructures

• 成果类型: Article
• 署名作者: Yoon, Yoseob; Lu, Zheyu; Uzundal, Can; Qi, Ruishi; Zhao, Wenyu; Chen, Sudi; Feng, Qixin; Kim, Woochang; Naik, Mit H.; Watanabe, Kenji; Taniguchi, Takashi; Louie, Steven G.; Crommie, Michael F.; Wang, Feng
• 署名单位: University of California System; University of California Berkeley; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; Northeastern University; University of California System; University of California Berkeley; University of California System; University of California Berkeley; National Institute for Materials Science; National Institute for Materials Science
• 刊物名称: Nature
• ISSN/ISSBN: 0028-4931
• DOI: 10.1038/s41586-024-07604-9
• 发表日期: 2024-07-25
• 关键词: breathing modes; generation; lattice; transmission; vibrations; graphite; graphene; shear

摘要

Phonon engineering at gigahertz frequencies forms the foundation of microwave acoustic filters1, acousto-optic modulators2 and quantum transducers3,4. Terahertz phonon engineering could lead to acoustic filters and modulators at higher bandwidth and speed, as well as quantum circuits operating at higher temperatures. Despite their potential, methods for engineering terahertz phonons have been limited due to the challenges of achieving the required material control at subnanometre precision and efficient phonon coupling at terahertz frequencies. Here we demonstrate the efficient generation, detection and manipulation of terahertz phonons through precise integration of atomically thin layers in van der Waals heterostructures. We used few-layer graphene as an ultrabroadband phonon transducer that converts femtosecond near-infrared pulses to acoustic-phonon pulses with spectral content up to 3 THz. A monolayer WSe2 is used as a sensor. The high-fidelity readout was enabled by the exciton-phonon coupling and strong light-matter interactions. By combining these capabilities in a single heterostructure and detecting responses to incident mechanical waves, we performed terahertz phononic spectroscopy. Using this platform, we demonstrate high-Q terahertz phononic cavities and show that a WSe2 monolayer embedded in hexagonal boron nitride can efficiently block the transmission of terahertz phonons. By comparing our measurements to a nanomechanical model, we obtained the force constants at the heterointerfaces. Our results could enable terahertz phononic metamaterials for ultrabroadband acoustic filters and modulators and could open new routes for thermal engineering. In an application of terahertz phonon engineering, terahertz phonons were generated, detected and manipulated through precise integration of atomically thin layers in van der Waals heterostructures.