Fig. 5: Evidence for intermediate valency in SmCoIn₅ below T_v ≈ 60 K.

a Temperature dependence of the momentum-resolved Res-ARPES spectra along the Γ − X − Γ high-symmetry cut at the Sm M₄ edge (hν = 1106 eV), showing an enhancement of the spectral weight near −2 < E_B < −0.5 eV that is associated with the appearance of the Sm²⁺ configuration (see Supplementary Note 2 and Supplementary Fig. 2). The emission patterns are consistent with the multiplet spectrum of Sm final states in the resonant ARPES process^52,53. b Momentum-integrated cuts along Γ − X − Γ as a function of binding energy, at the Sm M_4,5 resonant edges, for several temperatures below T_v ≈ 60 K. The peak structure near −2 < E_B < −0.5 eV associated with Sm²⁺ loses spectral weight as the temperature is increased. A nonresonant ARPES measurement carried out at T = 12 K with hν = 605 eV and integrated over the same momentum cut is shown offset at the bottom, which also contains Co and In bands. c X-ray photoemission spectroscopy at T = 12 K, showing an intermediate valence scenario.