@article{MorHerzogNoacketal.2018,
  author    = {Mor, Selene and Herzog, Marc and Noack, Johannes and Katayama, Naoyuki and Nohara, Minoru and Takagi, Hide and Trunschke, Annette and Mizokawa, Takashi and Monney, Claude and St{\"a}hler, Julia},
  title     = {Inhibition of the photoinduced structural phase transition in the excitonic insulator Ta2NiSe5},
  series = {Physical review : B, Condensed matter and materials physics},
  volume    = {97},
  journal   = {Physical review : B, Condensed matter and materials physics},
  number    = {11},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {2469-9950},
  doi       = {10.1103/PhysRevB.97.115154},
  pages     = {5},
  year      = {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 Gamma point of the Brillouin zone. The optical response saturates at a critical excitation fluence F-C = 0.30 +/- 0.08 mJ/cm(2) 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.},
  language  = {en}
}
@article{MorHerzogGolezetal.2017,
  author    = {Mor, Selene and Herzog, Marc and Golez, Denis and Werner, Philipp and Eckstein, Martin and Katayama, Naoyuki and Nohara, Minoru and Takagi, Hide and Mizokawa, Takashi and Monney, Claude and Staehler, Julia},
  title     = {Ultrafast Electronic Band Gap Control in an Excitonic Insulator},
  series = {Physical review letters},
  volume    = {119},
  journal   = {Physical review letters},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {0031-9007},
  doi       = {10.1103/PhysRevLett.119.086401},
  pages     = {11559 -- 11567},
  year      = {2017},
  abstract  = {We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor Ta2NiSe5 investigated by time-and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of F-C = 0.2 mJ cm(-2), the band gap narrows transiently, while it is enhanced above FC. Hartree-Fock calculations reveal that this effect can be explained by the presence of the low-temperature excitonic insulator phase of Ta2NiSe5, whose order parameter is connected to the gap size. This work demonstrates the ability to manipulate the band gap of Ta2NiSe5 with light on the femtosecond time scale.},
  language  = {en}
}