Thermoelectric response: Fluctuation in fermi temperature by stoichiometry variation in FeSe1-xTex superconductors

Abstract

Polycrystalline samples, FeSe1-xTex (x = 0.1, 0.4, 0.5, 0.6, 0.9), have been synthesized by the solid state reaction method and studied by means of X-ray diffraction, magnetization measurements and Seebeck measurements. As Te concentration increases, crystal structures change from FeSe-type to FeTe-type tetragonal structures. The optimal superconducting transition temperature (Tc) has been observed in the x = 0.5 and 0.6 samples. All the compounds exhibit an antiferromagnetic transition near ∼125 K. Compound with x = 0.5 shows the maximum value (absolute) in Seebeck coefficient as compared to others. Fermi temperature of all the compounds varies with Te substitution and found to be the lowest for the sample with the highest Tc. The ratio of Tc/TF indicates strong electronics correlations for the samples with optimal superconducting transitions pointing towards unconventional superconductivity.Polycrystalline samples, FeSe1-xTex (x = 0.1, 0.4, 0.5, 0.6, 0.9), have been synthesized by the solid state reaction method and studied by means of X-ray diffraction, magnetization measurements and Seebeck measurements. As Te concentration increases, crystal structures change from FeSe-type to FeTe-type tetragonal structures. The optimal superconducting transition temperature (Tc) has been observed in the x = 0.5 and 0.6 samples. All the compounds exhibit an antiferromagnetic transition near ∼125 K. Compound with x = 0.5 shows the maximum value (absolute) in Seebeck coefficient as compared to others. Fermi temperature of all the compounds varies with Te substitution and found to be the lowest for the sample with the highest Tc. The ratio of Tc/TF indicates strong electronics correlations for the samples with optimal superconducting transitions pointing towards unconventional superconductivity.