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 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 falls in the Bose-Einstein condensation regime of the excitonic insulator state.
- Received 4 March 2014
- Revised 24 September 2014
DOI:https://doi.org/10.1103/PhysRevB.90.155116
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