Study of magnetic fluctuations and nematic phase transition in BaFe$_{2}$As$_{2}$

We used high resolution AC micro-calorimetry and SQUID magnetometry to study the phase transitions in BaFe$_{2}$As$_{2}$ single crystals. A pronounced peak observed in the specific heat at T$_{\mathrm{N}}$ $\sim$ 132K, together with a step in the magnetization at the same temperature signifies the AFM/Structural transition in BaFe$_{2}$As$_{2}$. Annealing treatment of the sample shifts the peak in specific heat to 137K and reduces its width to $\sim$ 0.8K (FWHM). A thorough investigation of the specific heat up to 220K revealed no discernible, additional phase transitions above a typical background noise level of 5 to 10 $\times$ 10$^{-4}$ for $\Delta $C/C. However, strong in-plane magnetic fluctuations were observed to persist to as high as 180K in magnetization, which provide a possible explanation for previous reports of a nematic phase transition.