Ultrafast Control over Stiffening and Softening of Coherent Interlayer Coupling in WSe<sub>2</sub>/WS<sub>2</sub> Heterobilayers.
basic_science · Level V
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- Record sourced from PubMed, PMID 39663813.
- Also identified by DOI 10.1021/acs.nanolett.4c05079.
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Abstract
Twisted van der Waals heterostructures have led to emerging layer-dependent correlated physics in moiré potentials. While optoelectronic controls over interlayer electronic coupling have been reported, the concomitant interlayer vibration has not yet been controlled. Here, we report experimental evidence of ultrafast optical control over the amplitude and oscillation period of interlayer breathing phonons in WSe<sub>2</sub>/WS<sub>2</sub> heterobilayers. Femtosecond optical excitation above the Mott density in gate-tuned devices shows as large as 10% changes of stiffening and softening amplitude of coherent phonons. A theoretical model, incorporating both Buckingham and Hartree energies, is presented to elucidate the impact of charge-separated carriers generated by photoexcitation on phonon dynamics. This work, therefore, provides insights for extending optoelectronic engineering into the coherent phonons in moiré systems.