Direct observation of the superconducting energy gap in the optical conductivity of the iron pnictide superconductor Ba(Fe0.9Co0.1)(2)As-2

作者：Gorshunov B^*; Wu D; Voronkov A A; Kallina P; Iida K; Haindl S; Kurth F; Schultz L; Holzapfel B; Dressel M

来源：Physical Review B, 2010, 81(6): 060509.

DOI：10.1103/PhysRevB.81.060509

The temperature-dependent optical reflectivity and complex transmissivity of an epitaxially grown Ba(Fe0.9Co0.1)(2)As-2 thin film were measured over a wide frequency range (4-35 000 cm(-1)). The opening of the superconducting gap 2 Delta(0) = (3.7 +/- 0.3) meV is directly observed by vanishing optical conductivity at 30 cm(-1) for T < T-c = 20 K. While in this range the measured temperature- and frequency-dependent electrodynamic properties agree well with the BCS predictions of a nodeless order parameter, unexpectedly a strong quasiparticle absorption shows up below 1.5 meV. The spectral weight of the condensate 1.94 x 10(7) cm(-2) corresponds to a penetration depth lambda = 3600 angstrom.

• 出版日期2010-2