Excitonic insulator state in Ta2NiSe5 probed by photoemission spectroscopy

Y. Wakisaka*, T. Sudayama, K. Takubo, T. Mizokawa, M. Arita, H. Namatame, M. Taniguchi, N. Katayama, M. Nohara, H. Takagi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

201 Citations (Scopus)


We report on a photoemission study of Ta2NiSe5 that has a quasi-one-dimensional structure and an insulating ground state. Ni 2p core-level spectra show that the Ni 3d subshell is partially occupied and the Ni 3d states are heavily hybridized with the Se 4p states. In angle-resolved photoemission spectra, the valence-band top is found to be extremely flat, indicating that the ground state can be viewed as an excitonic insulator state between the Ni 3d-Se 4p hole and the Ta 5d electron. We argue that the high atomic polarizability of Se plays an important role to stabilize the excitonic state.

Original languageEnglish
Article number026402
JournalPhysical Review Letters
Issue number2
Publication statusPublished - 2009 Aug 6
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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