Fig. 3: Temperature dependence of the band structure and the Bardeen–Cooper–Schrieffer (BCS)-like behavior of the energy gap.
From: Evidence of high-temperature exciton condensation in a two-dimensional semimetal
a ARPES spectra along \(\overline{\Gamma {{{{{\rm{M}}}}}}}\,\) reveal the development of the flat valence band top and it shifts away from the Fermi level when the temperature is decreased from 300 to 10 K. The data were taken with 40 eV photons. b ARPES maps symmetrized in energy about the Fermi level show a gap in the condensed phase. c Symmetrized EDCs at the zone center at selected temperatures between 10 and 300 K. By symmetrization, the effect of Fermi–Dirac distribution at high temperatures can be canceled out. An example of the fit to a phenomenological BCS-type function34 is shown as a red dashed curve for the EDC obtained at 10 K. d The extracted temperature dependence of the square of the energy gap. The red curve is a fit using a BCS-type mean-field equation. Transition temperature TC is labeled. The error bar is deduced from the standard deviation of the fitting.
