Critical and Gaussian conductivity fluctuations in a BaFe1.9Ni0.1As2 superconductor

• Published in: Superconductor science & technology 2013-12, Vol.26 (12)
• Main Authors: Salem-Sugui Jr, S, Alvarenga, A D, Rey, R I, Mosqueira, J, Luo, H-Q, Lu, X-Y
• Format: Article
• Language: English
• Subjects: Collective modes (e.g., in one-dimensional conductors); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Conductivity phenomena in semiconductors and insulators; Electronic conduction in metals and alloys; Electronic transport in condensed matter; Exact sciences and technology; Mixed conductivity and conductivity transitions; Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves; Physics; Transport properties of condensed matter (nonelectronic)
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/26/12/125019

We study fluctuation conductivity in a single crystal of BaFe1.9Ni0.1As2 superconductor (Tc = 20 K) as a function of temperature and applied magnetic field. Magneto-conductivity curves, Δσ versus T, were analyzed in terms of −1 (dln(Δσ) dT) versus T plots, which allow us to study different fluctuation regimes and to estimate exponent values and temperature widths of each regime. The analysis of magneto-conductivity curves evidences the existence of only two fluctuation regimes, a possible critical one (of glass-like type) going from the irreversible temperature to above Tc(H), followed by Aslamazov-Larkin fluctuations in the Gaussian regime.