The coupling of the electron system to lattice vibrations and their time-dependent control and detection provide unique insight into the nonequilibrium physics of semiconductors. Here, we investigate the ultrafast transient response of semiconducting monolayer 2H-MoTe2 encapsulated with hBN 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 ∼20% of the maximum transient signal, due to the displacive excitation of the out-of-plane A1g phonon. Ab initio calculations reveal a dramatic rearrangement of the optical absorption of monolayer MoTe2 induced by an out-of-plane stretching and compression of the crystal lattice, consistent with an A1g -type oscillation. Our results highlight the extreme sensitivity of the optical properties of monolayer TMDs to small structural modifications and their manipulation with light.

Strong Coupling of Coherent Phonons to Excitons in Semiconducting Monolayer MoTe2

Khaustov, Vladislav O.;Coletti, Camilla;Cerullo, Giulio
2023

Abstract

The coupling of the electron system to lattice vibrations and their time-dependent control and detection provide unique insight into the nonequilibrium physics of semiconductors. Here, we investigate the ultrafast transient response of semiconducting monolayer 2H-MoTe2 encapsulated with hBN 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 ∼20% of the maximum transient signal, due to the displacive excitation of the out-of-plane A1g phonon. Ab initio calculations reveal a dramatic rearrangement of the optical absorption of monolayer MoTe2 induced by an out-of-plane stretching and compression of the crystal lattice, consistent with an A1g -type oscillation. Our results highlight the extreme sensitivity of the optical properties of monolayer TMDs to small structural modifications and their manipulation with light.
2023
Settore PHYS-03/A - Fisica sperimentale della materia e applicazioni
Coherent phonons; MoTe2; excitons; monolayer; transition metal dichalcogenides; two-dimensional materials; ultrafast spectroscopy
   Graphene Flagship Core Project 3
   GrapheneCore3
   European Commission
   Horizon 2020 Framework Programme
   881603

   ENhancing and prObing Strong light-matter Interactions in 2D materials by ultrafaSt optical techniques
   ENOSIS
   European Commission
   Horizon 2020 Framework Programme
   101029644

   Phase-matched nonlInear Optics iN layEred sEmiconductoRs
   PIONEER
   European Commission
   Horizon Europe Framework Programme
   101066108
File in questo prodotto:
File Dimensione Formato  
sayers-et-al-2023-strong-coupling-of-coherent-phonons-to-excitons-in-semiconducting-monolayer-mote2.pdf

accesso aperto

Tipologia: Published version
Licenza: Creative Commons
Dimensione 3.42 MB
Formato Adobe PDF
3.42 MB Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/151143
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 15
  • ???jsp.display-item.citation.isi??? 16
  • OpenAlex ND
social impact