Excitonic Bose-Einstein condensation in Ta2 NiSe5 above room temperature

K. Seki, Y. Wakisaka, T. Kaneko, T. Toriyama, T. Konishi, T. Sudayama, N. L. Saini, M. Arita, H. Namatame, M. Taniguchi, N. Katayama, Minoru Nohara, H. Takagi, T. Mizokawa, Y. Ohta

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Abstract

We show that finite temperature variational cluster approximation (VCA) calculations on an extended Falicov-Kimball model can reproduce angle-resolved photoemission spectroscopy (ARPES) results on Ta2NiSe5 across a semiconductor-to-semiconductor structural phase transition at 325 K. We demonstrate that the characteristic temperature dependence of the flat-top valence band observed by ARPES is reproduced by the VCA calculation on the realistic model for an excitonic insulator only when the strong excitonic fluctuation is taken into account. The present calculations indicate that Ta2NiSe5 falls in the Bose-Einstein condensation regime of the excitonic insulator state.

Original languageEnglish
Article number155116
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume90
Issue number15
DOIs
Publication statusPublished - Oct 13 2014

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ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Seki, K., Wakisaka, Y., Kaneko, T., Toriyama, T., Konishi, T., Sudayama, T., Saini, N. L., Arita, M., Namatame, H., Taniguchi, M., Katayama, N., Nohara, M., Takagi, H., Mizokawa, T., & Ohta, Y. (2014). Excitonic Bose-Einstein condensation in Ta2 NiSe5 above room temperature. Physical Review B - Condensed Matter and Materials Physics, 90(15), [155116]. https://doi.org/10.1103/PhysRevB.90.155116