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Ultrafast dynamics and coherent order parameter oscillations under photo-excitation in the excitonic insulator Ta2NiSe5

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Daniel Werdehausen, Steinn Y. Agustsson, Minjae Kim, Parmida Shabestari, Emily Huang, Amrit Pokharel, Timofei Larkin, Alexander Boris, Tomohiro Takayama, Yangfan Lu, Andreas W. Rost, Hao Chu, Alexander Yaresko, Marc Höppner, Armin Schulz, Dirk Manske, Bernhard Keimer, Hidenori Takagi, Stefan Kaiser

School/Research organisations


The excitonic insulator (EI) is an intriguing phase of condensed excitons undergoing a Bose-Einstein-Condensation (BEC)-type transition. A prominent candidate has been identified in Ta2NiSe5. Ultrafast spectroscopy allows tracing the coherent response of the EI condensate directly in the time domain. Probing the collective electronic response we can identify fingerprints for the Higgs-amplitude equivalent mode of the condensate. In addition we find a peculiar coupling of the EI phase to a low frequency phonon mode. We will discuss the transient response on multiple energies scales ranging from the exciton dynamics to the coherent THz response of the gap.



Original languageEnglish
Title of host publicationUltrafast Bandgap Photonics III
EditorsMichael K. Rafailov
Number of pages7
ISBN (Electronic)9781510617889
ISBN (Print)9781510617872
Publication statusPublished - 8 May 2018
EventUltrafast Bandgap Photonics III 2018 - Orlando, United States
Duration: 16 Apr 201819 Apr 2018

Publication series

NameProceedings of SPIE
PublisherSociety of Photo-optical Instrumentation Engineers
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceUltrafast Bandgap Photonics III 2018
CountryUnited States
Internet address

    Research areas

  • Collective excitation, Exciton wave packet, Excitonic insulator, Non-equilibrium, Pump-probe, THz, Time-domain, Ultrafast

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