Dresden 2011 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 36: SC: Fe-based Superconductors - 122 - Properties, Electronic Structure, Mechanisms

TT 36.15: Vortrag

Mittwoch, 16. März 2011, 18:00–18:15, HSZ 304

Highly anisotropic energy gap in superconducting Ba(Fe_0.9Co_0.1)₂As₂ from optical conductivity measurements — •A. V. Pronin¹, T. Fischer¹, J. Wosnitza¹, K. Iida², F. Kurth², S. Haindl², L. Schultz², B. Holzapfel², and E. Schachinger³ — ¹Dresden High Magnetic Field Laboratory (HLD), FZ Dresden-Rossendorf, 01314 Dresden, Germany — ²IFW Dresden, Institute for Metallic Materials, 01171 Dresden, Germany — ³Institute of Theoretical and Computational Physics, Graz University of Technology, 8010 Graz, Austria

We have measured the complex dynamical conductivity, σ = σ₁ + iσ₂, of superconducting Ba(Fe_0.9Co_0.1)₂As₂ (T_c = 22 K) in the terahertz and infrared ranges. The temperature dependence of σ₁ demonstrates a pronounced coherence peak at frequencies below 15 cm⁻¹ (1.8 meV). The temperature dependence of the penetration depth, calculated from σ₂, shows power-law behavior at the lowest temperatures. Analysis of the conductivity data with a two-gap model, gives the smaller isotropic s-wave gap of Δ_A = 3 meV, while the larger gap is highly anisotropic with possible nodes and its rms amplitude is Δ₀ = 8 meV. Overall, our results are consistent with a two-band superconductor with an s_± gap symmetry.