Femtosecond time-resolved midinfrared reflectivity is used to investigate the electron and phonon dynamics occurring at the direct band gap of the excitonic insulator Ta2NiSe5 below the critical temperature of its structural phase transition. We find that the phonon dynamics show a strong coupling to the excitation of free carriers at the Γ point of the Brillouin zone. The optical response saturates at a critical excitation fluence FC=0.30±0.08 mJ/cm2 due to optical absorption saturation. This limits the optical excitation density in Ta2NiSe5 so that the system cannot be pumped sufficiently strongly to undergo the structural change to the high-temperature phase. We thereby demonstrate that Ta2NiSe5 exhibits a blocking mechanism when pumped in the near-infrared regime, preventing a nonthermal structural phase transition.

Mor, S., Herzog, M., Noack, J., Katayama, N., Nohara, M., Takagi, H., Trunschke, A., Mizokawa, T., Monney, C., Stahler, J., Inhibition of the photoinduced structural phase transition in the excitonic insulator Ta2NiSe5, <<PHYSICAL REVIEW. B>>, 2018; 97 (11): 115154-115158. [doi:10.1103/PhysRevB.97.115154] [http://hdl.handle.net/10807/203372]

Inhibition of the photoinduced structural phase transition in the excitonic insulator Ta2NiSe5

Mor, Selene
;
2018

Abstract

Femtosecond time-resolved midinfrared reflectivity is used to investigate the electron and phonon dynamics occurring at the direct band gap of the excitonic insulator Ta2NiSe5 below the critical temperature of its structural phase transition. We find that the phonon dynamics show a strong coupling to the excitation of free carriers at the Γ point of the Brillouin zone. The optical response saturates at a critical excitation fluence FC=0.30±0.08 mJ/cm2 due to optical absorption saturation. This limits the optical excitation density in Ta2NiSe5 so that the system cannot be pumped sufficiently strongly to undergo the structural change to the high-temperature phase. We thereby demonstrate that Ta2NiSe5 exhibits a blocking mechanism when pumped in the near-infrared regime, preventing a nonthermal structural phase transition.
2018
Inglese
Mor, S., Herzog, M., Noack, J., Katayama, N., Nohara, M., Takagi, H., Trunschke, A., Mizokawa, T., Monney, C., Stahler, J., Inhibition of the photoinduced structural phase transition in the excitonic insulator Ta2NiSe5, <<PHYSICAL REVIEW. B>>, 2018; 97 (11): 115154-115158. [doi:10.1103/PhysRevB.97.115154] [http://hdl.handle.net/10807/203372]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

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/10807/203372
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 34
  • ???jsp.display-item.citation.isi??? 35
social impact