Seminarium Międzynarodowego Laboratorium Silnych Pól Magnetycznych i Niskich Temperatur PAN
ul. Gajowicka 95, sala seminaryjna (nowy budynek, II piętro)
Fluctuation conductivity and possible pseudogap state in FeAs-based superconductor EuFeAsO0.85F0.15
L. V. Omelchenko, A. L. Solovjov, A. V. Terekhov, E.P. Khlybov and K. Rogacki
B. I.Verkin Institute for Low Temperature Physics and Engineering of National, Academy of Science of Ukraine
The study of excess conductivity σ΄(T) in the textured polycrystalline FeAs-based superconductor EuFeAsO0.85F0.15 (Tc = 11K) prepared by the solid state synthesis is reported. The σ'(T) analysis has been performed within the Local Pair (LP) model. Near Tc σ'(T) is described by the 3D term of the Aslamasov-Larkin theory. Above the crossover temperature T0 ? 11.7K σ'(T) is described by the 2D Maki-Thompson (MT) fluctuation term of the Hikami-Larkin (HL) theory. But enhanced 2D-MT fluctuation contribution, being typical for the magnetic superconductors, is observed.
Within the LP model approach the PG parameter, Δ*(T), was determined for the first time. Δ*(T) shows the narrow maximum at Ts ?160K followed by the linear drop down to TSDW = TNFe ? 133K. Both small ΔT3D, enhanced σ'(T) and linear Δ*(T) drop are considered to be the evidence of the enhanced magnetic interaction in EuFeAsO0.85F0.15.
