Annealing effects on the crystal structure and physical properties of FeSe1?xTex (0.6 ≦ x ≦ 1) single crystals |
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Authors: | M Imaizumi T Noji T Adachi Y Koike |
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Institution: | 1. Superconductivity Research Laboratory/ISTEC, Tokyo, Japan;2. Waseda University, Tokyo, Japan |
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Abstract: | Annealing effects of FeSe1?xTex (0.6 ≦ x ≦ 1) single crystals have been investigated from measurements of the powder X-ray diffraction and specific heat. Through the annealing, several peaks of powder X-ray diffraction have become sharp and a clean jump of the specific-heat at the superconducting (SC) transition temperature, Tc, has been observed for x = 0.6–0.9, indicating bulk superconductivity. For annealed single-crystals of x = 0.6–0.8, the SC condensation energy, U0, and the SC gap, Δ0, at 0 K have been estimated as ~1.8 J/mol and 2.3–2.5 meV, respectively. The value of 2Δ0/kBTc is 3.9–4.5, indicating a little strong-coupling superconductivity. Both the electronic specific-heat coefficient in the normal state, γn, and the residual electronic specific-heat coefficient in the SC state, γ0, have been found to show significant x dependence. The values of γn are much larger than those estimated from the band calculation. |
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