Ultrafast Electronic Band Gap Control in an Excitonic Insulator

Selene Mor, Marc Herzog, Denis GoleŽ, Philipp Werner, Martin Eckstein, Naoyuki Katayama, Minoru Nohara, Hide Takagi, Takashi Mizokawa, Claude Monney, Julia Stähler

Research output: Contribution to journalArticlepeer-review

119 Citations (Scopus)


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 FC=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.

Original languageEnglish
Article number086401
JournalPhysical Review Letters
Issue number8
Publication statusPublished - Aug 23 2017

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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