Figure 1: Specific heat of YBa2Cu3O6.54.
Temperature dependence of the specific heat for the indicated magnetic fields 
with ΔCp(H, T)=Cp(H, T)−Cp(Hmax, T) and Hmax=14 T. The temperature TCp corresponding to the maximum of the specific heat anomaly has been reported in Fig. 2 (solid (red) symbols). The shape of the anomaly and its evolution in magnetic field are characteristics of the superconducting transition in the presence of large thermal fluctuations. Inset: ΔCp(0,T)/T as a function of T from the 0-T temperature sweep (purple line, same as main panel, Hmax=14 T) and the magnetic field sweeps displayed in Fig. 3 (blue symbols, Hmax=26 T). The solid squares have been deduced from relaxation data and the open circles from the modulation technique data (see Fig. 3). As shown, the two sets of data are consistent with the entropy balance law as the blue and purple areas are identical. The error bars represent the systematic uncertainties, were estimated along the different calibrations steps, and are dominated by the field dependence of the addenda contribution.
