The fluctuation effect of BaFe1.8Co0.2As2 single crystals from reversible magnetization

초록

We present reversible magnetization measurements for applied fields in the range from 0.5 to 7 T made while varying the temperature for optimally doped BaFe1.8Co0.2As2 single crystals with T-c = 23.6 K. The rounding fluctuating magnetization was observed in the reversible range of magnetization for temperatures above 18 K. This fluctuation effect is quite small compared with that in high temperature cuprate superconductors, but is still large enough for obtaining the essence of the physical properties in this iron pnictide superconductor. This reversible magnetic fluctuation follows a three-dimensional scaling form in the critical fluctuation region for fields above 0.5 T, which indicates that this iron pnictide superconductor belongs to the class of three-dimensional superconductors.

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