Strong Coupling of Coherent Phonons to Excitons in Semiconducting Monolayer MoTe${}_2$

Abstract

The coupling of the electron system to lattice vibrations and their time-dependent control and detection provides unique insight into the non-equilibrium physics of semiconductors. Here, we investigate the ultrafast transient response of semiconducting monolayer 2$H$-MoTe${}_2$ encapsulated with $h$BN using broadband optical pump-probe microscopy. The sub-40-fs pump pulse triggers extremely intense and long-lived coherent oscillations in the spectral region of the A' and B' exciton resonances, up to $\sim$20% of the maximum transient signal, due to the displacive excitation of the out-of-plane $A_{1g}$ phonon. Ab-initio calculations reveal a dramatic rearrangement of the optical absorption of monolayer MoTe${}_2$ induced by an out-of-plane stretching and compression of the crystal lattice, consistent with an $A_{1g}$-type oscillation. Our results highlight the extreme sensitivity of the optical properties of monolayer TMDs to small structural modifications and their manipulation with light.

27 pages, 4 figures, supporting information

References in corpus (6)

• Field-Effect Transistors Based on Few-Layered alpha-MoTe_2
• Coupled Ferroelectricity and Superconductivity in Bilayer $T_d$-MoTe${}_2$
• Ab initio calculations of ultra-short carrier dynamics in 2D materials: valley depolarization in single-layer WSe${}_2$
• Ultrafast coherent interlayer phonon dynamics in atomically thin layers of MnBi2Te4
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Cited by in corpus (7)

• Strain-induced activation of chiral-phonon emission in monolayer WS${}_2$
• Theory of coherent phonons coupled to excitons
• Slow Dephasing of Coherent Optical Phonons in Two-dimensional Lead Organic Chalcogenides
• Coherent Modulation of Two-Dimensional Moiré States with On-Chip THz Waves
• Effect of photoinduced screening on the spectroscopic signature of exciton-phonon coupling
• Anomalous amplitude mode dynamics below the expected charge-density-wave transition in 1$T$-VSe${}_2$
• Excitonic effects in the photocarriers dynamics of two-dimensional materials