Superconducting Properties of a Stoichiometric FeSe Compound and Two Anomalous Features in the Normal State

초록

This paper reports the superconducting behavior of the tetragonal iron-chalcogenide superconductor FeSe. The electrical resistivity and the magnetic moment measurements confirmed its superconductivity with T-c(zero) and T-c(wag) of K under ambient pressure. Electron probe macro analysis indicated that the sample had a stoichiometric re:Se ratio or The Seebeck coefficient. which was 12.3 mu V/K at; room temperature, changed to it negative vain,: near 200 K indicating it to he a two-carrier material. Above T-c, the rho(T) curve, revealed an 'S' shape, and d rho(T)/dT and d(2)rho(T)/T-2 showed two anomalous features. one near T-an = 30 K and the other near T. = 110 K. The Seebeck coefficient, S(T), also displays peculiar behavior near the T-an and T*. We also report a rather smaller critical current density. J(c) = 10(2) similar to 10(4) A/cm(2), compared to those observed for the other pnictides and doped chalcogenides.

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