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Direct observation of the superconducting energy gap in the optical conductivity of the iron pnictide superconductor Ba(Fe0.9Co0.1)2As2

B. Gorshunov, D. Wu, A. A. Voronkov, P. Kallina, K. Iida, S. Haindl, F. Kurth, L. Schultz, B. Holzapfel, and M. Dressel
Phys. Rev. B 81, 060509(R) – Published 25 February 2010

Abstract

The temperature-dependent optical reflectivity and complex transmissivity of an epitaxially grown Ba(Fe0.9Co0.1)2As2 thin film were measured over a wide frequency range (435000cm1). The opening of the superconducting gap 2Δ0=(3.7±0.3)meV is directly observed by vanishing optical conductivity at 30cm1 for T<Tc=20K. 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 1.94×107cm2 corresponds to a penetration depth λ=3600Å.

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  • Received 6 December 2009

DOI:https://doi.org/10.1103/PhysRevB.81.060509

©2010 American Physical Society

Authors & Affiliations

B. Gorshunov1,2, D. Wu1,*, A. A. Voronkov2, P. Kallina1, K. Iida3, S. Haindl3, F. Kurth3, L. Schultz3, B. Holzapfel3, and M. Dressel1

  • 11. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
  • 2Prokhorov Institute of General Physics, Russian Academy of Sciences, Vavilov Street 38, 119991 Moscow, Russia
  • 3IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden, Germany

  • *dan.wu@pi1.physik.uni-stuttgart.de

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Issue

Vol. 81, Iss. 6 — 1 February 2010

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