A BCS-like gap in the superconductor SmFeAsO0.85F0.15.

摘要: Since the discovery of superconductivity in high-transition-temperature (high-T(c)) copper oxides two decades ago, it has been firmly established that CuO(2) plane is essential for and gives rise to a host other very unusual properties. A new family superconductors with general composition LaFeAsO(1-x)F(x) recently discovered conspicuous lack planes raises tantalizing question different pairing mechanism these oxypnictides. The superconducting gap (its magnitude, structure, temperature dependence) intimately related pairing. Here we report observation single superconductor SmFeAsO(0.85)F(0.15) T(c) = 42 K as measured by Andreev spectroscopy. value 2Delta 13.34 +/- 0.3 meV 2Delta/k(B)T(c) 3.68 (where k(B) Boltzmann constant), close Bardeen-Cooper-Schrieffer (BCS) prediction 3.53. decreases vanishes at manner consistent BCS prediction, but dramatically from pseudogap behaviour oxide superconductors. Our results clearly indicate nodeless order parameter, which nearly isotropic size across sections Fermi surface, are not compatible models involving antiferromagnetic fluctuations, strong correlations, t-J model, like, originally designed high-T(c) oxides.