Inhibition of the photoinduced structural phase transition in the excitonic insulator ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$

Mor, Selene; Herzog, Marc; Noack, Johannes; Katayama, Naoyuki; Nohara, Minoru; Takagi, Hide; Trunschke, Annette; Mizokawa, Takashi; Monney, Claude; Stähler, Julia

doi:10.1103/PhysRevB.97.115154

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Journal article

Inhibition of the photoinduced structural phase transition in the excitonic insulator ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$

Mor, Selene Department of Physical Chemistry, Fritz-Haber-Institut der MPG, Berlin, Germany
Herzog, Marc Department of Physical Chemistry, Fritz-Haber-Institut der MPG, Berlin, Germany - Institute for Physics and Astronomy, University of Potsdam, Germany
Noack, Johannes Department of Inorganic Chemistry, Fritz-Haber-Institut der MPG, Berlin, Germany
Katayama, Naoyuki Department of Physical Science and Engineering, Nagoya University, Japan
Nohara, Minoru Research Institute for Interdisciplinary Science, Okayama University, Japan
Takagi, Hide Max Planck Institute for Solid State Research, Stuttgart, Germany - Department of Physics, University of Tokyo, Japan
Trunschke, Annette Department of Inorganic Chemistry, Fritz-Haber-Institut der MPG, Berlin, Germany
Mizokawa, Takashi Department of Applied Physics, Waseda University, Tokyo, Japan
Monney, Claude Department of Physics, University of Fribourg, Switzerland
Stähler, Julia Department of Physical Chemistry, Fritz-Haber-Institut der MPG, Berlin, Germany

26.03.2018

Published in:

Physical Review B. - 2018, vol. 97, no. 11, p. 115154

English 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.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

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