title: Probing transport mechanisms of BaFe₂As₂ superconducting films and grain boundary junctions by noise spectroscopy.
abstract: An important step forward for the understanding of high-temperature superconductivity has been the discovery of iron-based superconductors. Among these compounds, iron pnictides could be used for high-field magnet applications, resulting more advantageous over conventional superconductors, due to a high upper critical field as well as its low anisotropy at low temperatures. However, the principal obstacle in fabricating high quality superconducting wires and tapes is given by grain boundaries. In order to study these effects, the dc transport and voltage-noise properties of Co-doped BaFe₂As₂ superconducting films with artificial grain boundary junctions have been investigated. A specific procedure allows the separation of the film noise from that of the junction. While the former shows a standard 1/f behaviour, the latter is characterized by an unconventional temperature-dependent multi-Lorentzian voltage-spectral density. Moreover, below the film superconducting critical temperature, a peculiar noise spectrum is found for the grain boundary junction. Possible theoretical interpretation of these phenomena is proposed.
authors.affiliation: 1] Dipartimento di Fisica "E.R. Caianiello", Università di Salerno, I-84084 Fisciano, Salerno, Italy [2] CNR-SPIN Salerno, Università di Salerno, I-84084 Fisciano, Salerno, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Barone
authors.affiliation: 1] Dipartimento di Fisica "E.R. Caianiello", Università di Salerno, I-84084 Fisciano, Salerno, Italy [2] CNR-SPIN Salerno, Università di Salerno, I-84084 Fisciano, Salerno, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Romeo
authors.affiliation: 1] Dipartimento di Fisica "E.R. Caianiello", Università di Salerno, I-84084 Fisciano, Salerno, Italy [2] CNR-SPIN Salerno, Università di Salerno, I-84084 Fisciano, Salerno, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Pagano
authors.affiliation: CNR-SPIN Salerno, Università di Salerno, I-84084 Fisciano, Salerno, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Adamo
authors.affiliation: CNR-SPIN Napoli, Via Campi Flegrei 34, I-80078 Pozzuoli, Napoli, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Nappi
authors.affiliation: CNR-SPIN Napoli, Via Campi Flegrei 34, I-80078 Pozzuoli, Napoli, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Sarnelli
authors.affiliation: Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW) Dresden, PO Box 270116, 01171 Dresden, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Kurth
authors.affiliation: Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW) Dresden, PO Box 270116, 01171 Dresden, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Iida