fixed temperature, a strong relaxation occurs. As shown in the inset of the figure where the magnetization is plotted as a function of time, at 155 mK, the equilibrium value is reached after times as long as 600 s.

Figure \[fig2\]a shows the equilibrium values of the magnetization at the transition (obtained from figure \[fig1\]) as a function of temperature for the single crystal. It can be seen that a small hysteresis is present (which is much narrower than for a fast temperature sweep), indicating a first-order like behavior. Also shown is the specific heat data on the same crystal. A subtle change of slope occurs in the magnetization at the peak in specific heat, while the first-order transition develops below this peak. The bump observed at $\approx$180 mK before the sharp increase is not present in the magnetization of the powder sample as shown in figure \[fig2\]b and might be due to a sample inhomogeneity, a consequence of difficulties in sample preparation [@Ross11b; @Yaouanc11].

From the magnetization, it appears, that the first-order transition occurs around 150 mK in this single crystal. The transition extends over about 20 mK and the hysteresis width is about 3 mK. For the powder 