Fig. 2

Temperature dependence of the folded valence bands and the CDW transition temperature. a ARPES map around \(\overline {\rm{M}} \) at the zone boundary taken at 10 K. The red and blue curves indicate the (2 × 2) folded valence bands and the conduction band, respectively, on the left side only, assuming that the bands do not interact. b Second-derivative map of the same data, which highlights the band dispersions. The red dashed box indicates a region of interest used for integrating the ARPES intensity as a measure of the folded-band intensity. c–f ARPES maps taken at 50, 80, 100, and 150 K, respectively. The folded valence bands diminish as T increases. g Integrated ARPES intensities over the region of interest as a function of temperature for the 1-TL, 2-TL, and 3-TL and bulk TiTe₂ samples. The error bar is deduced from the s.d. of the fitting. The blue curve is a fit using a mean-field equation described in the text