Single Molecule Metamagnetism and the Single Energy Scale Model

Measurements of the magnetization isotherms at low temperatures are used to extract the linear, $\chi_{1}$ and third order, $\chi _{3}$, magnetic susceptibilities of two distinct single molecule magnets (SMM), (UO$_{2}$-L)$_{3}$ and Cr$_{9}$F$_{11}$. In (UO$_{2}$-L)$_{3}$ the behavior of $\chi_{3}$ is consistent with a peak appearing at a temperature T$_{3}$ which is $\sim$ 0.5 T$_{1}$ the temperature at which a peak in $\chi_{1}$ is observed. In Cr$_{9}$F$_{11}$ a peak in $\chi _{1}$ is not present neither is a peak in $\chi_{3}$ observed. Nevertheless, a simple phenomenological model with only a single energy scale, is able to account for the two distinct behaviors in the linear and nonlinear magnetic response of these two SMMs.