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arXiv · 2602.21156

Acoustic Guided Waves in MoS2 thin flakes

Martín Aversa·Nicolás Roqueiro·Camila Borrazás·Juan Ignacio Sangiorgio·Hilario D. Boggiano·Juan Bonaparte·Andrés Di Donato·María Cecilia Fuertes·Andrea V. Bragas·Gustavo Grinblat
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Abstract

Guided acoustic waves in two-dimensional materials are a key channel for energy transport and dissipation, yet their generation and propagation in transition metal dichalcogenides remain poorly understood. Here, we employ in-situ and spatially decoupled ultra-fast optical pump-probe techniques to investigate guided waves in MoS2 flakes with thicknesses between 90 and 410 nm. We observe a propagating acoustic excitation with a constant velocity of (6.7 +/- 0.8) km/s, independent of thickness. Finite element simulations and symmetry analysis reveal that these vibrations deviate from the classical Lamb wave model and are better described as a superposition of decoupled longitudinal and shear modes. We show that their optical detectability is governed by the Poisson effect: longitudinal components modulate the flake thickness and generate a measurable signal, whereas shear motion remains largely optically invisible. An intrinsic attenuation length of approximately 3.3 microns indicates that dissipation is dominated by material-specific mechanisms rather than geometric spreading. Finally, we demonstrate remote excitation across a nanometric step, enabling acoustic generation in optically inaccessible regions. These results provide a foundation for nanoscale phononic circuits and engineered in-plane energy transport in 2D-based optomechanical and quantum acoustic devices.

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Martín Aversa, Nicolás Roqueiro, Camila Borrazás, Juan Ignacio Sangiorgio, Hilario D. Boggiano, Juan Bonaparte, Andrés Di Donato, María Cecilia Fuertes, Andrea V. Bragas, Gustavo Grinblat. 2026-02-24. Acoustic Guided Waves in MoS2 thin flakes. https://arxiv.org/abs/2602.21156

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