title: Multigap superconductivity and strong electron-boson coupling in Fe-based superconductors: a point-contact Andreev-reflection study of Ba(Fe(1-x)Co(x))2As2 single crystals.
abstract: Directional point-contact Andreev-reflection measurements in Ba(Fe(1-x)Co(x))2As2 single crystals (T(c) = 24.5 K) indicate the presence of two superconducting gaps with no line nodes on the Fermi surface. The point-contact Andreev-reflection spectra also feature additional structures related to the electron-boson interaction, from which the characteristic boson energy Ω(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 Ω(0) = 12 meV ≃ Ω(b)(0).
authors.affiliation: Dipartimento di Fisica, Politecnico di Torino, 10129 Torino, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Tortello
authors.forename: D
authors.initials: D
authors.lastname: Daghero
authors.forename: G A
authors.initials: GA
authors.lastname: Ummarino
authors.forename: V A
authors.initials: VA
authors.lastname: Stepanov
authors.forename: J
authors.initials: J
authors.lastname: Jiang
authors.forename: J D
authors.initials: JD
authors.lastname: Weiss
authors.forename: E E
authors.initials: EE
authors.lastname: Hellstrom
authors.forename: R S
authors.initials: RS
authors.lastname: Gonnelli