3 research outputs found
Possibility of local pair existence in optimally doped SmFeAsO(1-x) in pseudogap regime
We report the analysis of pseudogap Delta* derived from resistivity
experiments in FeAs-based superconductor SmFeAsO(0.85), having a critical
temperature T_c = 55 K. Rather specific dependence Delta*(T) with two
representative temperatures followed by a minimum at about 120 K was observed.
Below T_s = 147 K, corresponding to the structural transition in SmFeAsO,
Delta*(T) decreases linearly down to the temperature T_AFM = 133 K. This last
peculiarity can likely be attributed to the antiferromagnetic (AFM) ordering of
Fe spins. It is believed that the found behavior can be explained in terms of
Machida, Nokura, and Matsubara (MNM) theory developed for the AFM
superconductors.Comment: 5 pages, 2 figure
Paraconductivity of K-doped SrFe2As2 superconductor
Paraconductivity of the optimally K-doped SrFe2As2 superconductor is
investigated within existing fluctuation mechanisms. The in-plane excess
conductivity has been measured in high quality single crystals, with a sharp
superconducting transition at Tc=35.5K and a transition width less than 0.3K.
The data have been also acquired in external magnetic field up to 14T. We show
that the fluctuation conductivity data in zero field and for temperatures close
to Tc, can be explained within a three-dimensional Lawrence-Doniach theory,
with a negligible Maki-Thompson contribution. In the presence of the magnetic
field, it is shown that paraconductivity obeys the three-dimensional
Ullah-Dorsey scaling law, above 2T and for H||c. The estimated upper critical
field and the coherence length nicely agree with the available experimental
data.Comment: 12 pages, 5 figure