Two-gap superconductivity in Ba_1-xK_xFe_2As_2: A complementary study of the magnetic penetration depth by \muSR and ARPES

R. Khasanov; D. V. Evtushinsky; A. Amato; H. -H. Klauss; H. Luetkens; Ch. Niedermayer; B. Büchner; G. L. Sun; C. T. Lin; J. T. Park; D. S. Inosov; V. Hinkov

doi:10.1103/physrevlett.102.187005

arXiv · 0901.2329

Two-gap superconductivity in Ba_1-xK_xFe_2As_2: A complementary study of the magnetic penetration depth by \muSR and ARPES

R. Khasanov·D. V. Evtushinsky·A. Amato·H. -H. Klauss·H. Luetkens·Ch. Niedermayer·B. Büchner·G. L. Sun·C. T. Lin·J. T. Park·D. S. Inosov·V. Hinkov

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Abstract

We investigate the magnetic penetration depth \lambda in superconducting Ba_1-xK_xFe_2As_2 (T_c\simeq32K) with muon-spin rotation (\muSR) and angle-resolved photoemission (ARPES). Using \muSR, we find the penetration-depth anisotropy \gamma_\lambda=\lambda_c/\lambda_{ab} and the second-critical-field anisotropy \gamma_{H_c2} to show an opposite T-evolution below T_c. This dichotomy resembles the situation in the two-gap superconductor MgB_2. A two-gap scenario is also suggested by an inflection point in the in-plane penetration depth \lambda_ab around 7K. The complementarity of \muSR and ARPES allows us to pinpoint the values of the two gaps and to arrive to a remarkable agreement between the two techniques concerning the full T-evolution of \lambda_ab. This provides further support for the described scenario and establishes ARPES as a tool to assess macroscopic properties of the superconducting condensate.

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R. Khasanov, D. V. Evtushinsky, A. Amato, H. -H. Klauss, H. Luetkens, Ch. Niedermayer, B. Büchner, G. L. Sun, C. T. Lin, J. T. Park, D. S. Inosov, V. Hinkov. 2009-01-15. Two-gap superconductivity in Ba_1-xK_xFe_2As_2: A complementary study of the magnetic penetration depth by \muSR and ARPES. https://doi.org/10.1103/physrevlett.102.187005

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