Fig. 4: Evolution of electronic structure and correlations in FeSe_1−xTe_x.

a Phase diagram of FeSe_1−xTe_x, indicating the nematic phase transition (T_s, orange squares), the superconducting transition (T_c, blue points) and the antiferromagnetic phase transition (T_N, red points). Data points are taken from refs. ^5,53,30,60. b Fermi energies as a function of composition, x, for the α band (solid red squares), β band (solid and open green circles extracted from the linear horizontal (LH) and linear vertical (LV) spectra) and γ band (solid blue rhombuses). Additional points for γ band are from refs. ³¹ (blue triangles) and³⁰ (diamonds). The solid red and green lines are linear fits, while the blue curve is a 5^th order polynomial fit. c Effective masses as a function of composition, x, where the symbols are defined as in b. The solid red and green lines are linear fits, while the blue curve is the phenomenological fit detailed in the discussion. In b and c only Γ data are shown, where the error bars are calculated from the covariance values produced within the non-linear least squares fitting function. d Fermi surface map of the first Brillouin zone for x = 0.33 taken at 10 K using angle-resolved photoemission spectroscopy with LH polarisation. The spectra outside of the dashed box is enhanced by a factor of 2.5. e Schematic Fermi surface indicating the dominant orbital character of each potion of the bands and potential pairing channels.