We report on the specific heat determination of the anisotropic phase diagram of single crystals of optimally doped SmFeAsO1-xFx. In zero-field, the optimally doped compound displays a clear cusp-like anomaly in C/T with {\Delta}C/Tc = 24 mJ/molK2 at Tc = 49.5 K. In magnetic fields applied along the c-axis, we find pronounced superconducting fluctuations induced broadening and suppression of the specific heat anomaly which can be described using three-dimensional lowest-Landau-level scaling with an upper critical field slope of -3.5 T/K and an anisotropy of {\Gamma} = 8. The small value of {\Delta}C/Tc yields a Sommerfeld coefficient {\gamma} ~ 8 mJ/molK2 indicating that SmFeAsO1-xFx is characterized by a modest density of states and strong coupling.
@article{arxiv.1101.6027,
title = {Anisotropic Phase Diagram and Superconducting Fluctuations in SmFeAsO0.85F0.15},
author = {U. Welp and C. Chaparro and A. E. Koshelev and W. K. Kwok and A. Rydh and N. D. Zhigadlo and J. Karpinski and S. Weyeneth},
journal= {arXiv preprint arXiv:1101.6027},
year = {2011}
}