Through a direct comparison of specific heat and magnetoresistance, we critically asses the nature of superconducting fluctuations in the same nanogram crystal of SmFeAs(O,F). We show that although the superconducting fluctuation contribution to conductivity scales well within the two-dimensional lowest Landau level (2D-LLL) scheme, its predictions contrast with the inherently 3D nature of SmFeAs(O,F) in the vicinity of $T_c$. Furthermore, the transition seen in specific heat cannot be satisfactory described either by the LLL or the $XY$ scaling. Additionally we have validated, through comparing $H_{c2}$ values obtained from the entropy conservation construction ($H_{c2//ab}=-19.5\mathrm{T}/\mathrm{K}$ and $H_{c2//c}=-2.9\mathrm{T}/\mathrm{K})$, the analysis of fluctuation contribution to conductivity as a reasonable method for estimating the $H{}_{c2}$ slope.

• Received 19 May 2017
• Revised 15 August 2017

DOI:https://doi.org/10.1103/PhysRevB.96.104511