The electronic specific heat of as-grown and annealed single-crystals of FeSe 1-x Te x (0.6 ≤ x ≤ 1) has been investigated. It has been found that annealed single-crystals with x = 0.6 -0.9 exhibit bulk superconductivity with a clear specific-heat jump at the superconducting (SC) transition temperature, T c . Both 2Δ 0 /k B T c [Δ 0 : the SC gap at 0 K estimated using the single-band BCS s-wave model]and ⊿C/(γ n -γ 0 )T c [⊿C: the specific-heat jump at T c , γ n : the electronic specific-heat coefficient in the normal state, γ 0 : the residual electronic specific-heat coefficient at 0 K in the SC state] are largest in the well-annealed single-crystal with x = 0.7, i.e., 4.29 and 2.76, respectively, indicating that the superconductivity is of the strong coupling. The thermodynamic critical field has also been estimated. γ n has been found to be one order of magnitude larger than those estimated from the band calculations and increases with increasing x at x = 0.6 -0.9, which is surmised to be due to the increase in the electronic effective mass, namely, the enhancement of the electron correlation. It has been found that there remains a finite value of γ 0 in the SC state even in the well-annealed single-crystals with x = 0.8 -0.9, suggesting an inhomogeneous electronic state in real space and/or momentum space.

[1] It is found that the possibly achieved higher accuracy cannot be obtained for all overlapping bands if only one scheme is used to treat them in atmospheric absorption calculations. The commonly used multiplication transmittance scheme is not acceptable when correlation existing in the practical absorption spectra becomes strong. Therefore an optimized scheme to obtain k distribution parameters for overlapping bands is developed in this paper based on the completely uncorrelated, perfectly correlated, and partly correlated schemes. Two partial correlation formulae are given in the paper. Calculations of radiative flux and atmospheric heating (or cooling) rate are validated in detail using a line-by-line model described in the paper for six model atmospheres. The optimized scheme developed here has an accuracy in longwave clear skies of 0.

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