Fig. 2: Temperature dependence of magnetization M(T) and specific heat C(T) at different magnetic fields.

a,c, T-dependent M/H for H ≤ Hs (a) and H ≥ Hs (c). The arrows in a represent Tc determined from the singularity in dM/dT (e,f). b,d, T-dependent C/T for H ≤ Hs (b) and H ≥ Hs (d). Open triangles in b mark the onset temperature for thermal fluctuations towards Tc, where C/T starts to deviate from the constant behaviour upon cooling. e,f, T-dependence of the derivative of magnetization dM/dT below (e) and above (f) 3 T, respectively. The data at each field in e are shifted by 0.2 Am2 K−1 mol−1 for clarity.