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arXiv · 1009.1572

Multigap superconductivity and strong electron-boson coupling in Fe-based superconductors: A point-contact Andreev-reflection study of Ba(Fe1-xCox)2As2 single crystals

M. Tortello·D. Daghero·G. A. Ummarino·V. A. Stepanov·J. Jiang·J. D. Weiss·E. E. Hellstrom·R. S. Gonnelli
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Abstract

Directional point-contact Andreev-reflection (PCAR) measurements in Ba(Fe1-xCox)2As2 single crystals (Tc=24.5 K) indicate the presence of two superconducting gaps with no line nodes on the Fermi surface. The PCAR spectra also feature additional structures related to the electron-boson interaction, from which the characteristic boson energy Omega_b(T) is obtained, very similar to the spin-resonance energy observed in neutron scattering experiments. Both the gaps and the additional structures can be reproduced within a three-band s+- Eliashberg model by using an electron-boson spectral function peaked at Omega_0 = 12 meV ~ Omega_b(0).

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M. Tortello, D. Daghero, G. A. Ummarino, V. A. Stepanov, J. Jiang, J. D. Weiss, E. E. Hellstrom, R. S. Gonnelli. 2010-11-04. Multigap superconductivity and strong electron-boson coupling in Fe-based superconductors: A point-contact Andreev-reflection study of Ba(Fe1-xCox)2As2 single crystals. https://doi.org/10.1103/physrevlett.105.237002

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