Logarithmic Corrections to Tricritical Scaling in the Metamagnet FeCl2

A detailed study of the uniform magnetization of Fe${\mathrm{Cl}}_2$ in the vicinity of the tricritical point shows deviations from classical scaling behavior. The deviations are shown to be remedied by logarithmic corrections derived by graphical methods, but not by those from approximate recursion relations. This is the first observation of logarithmic corrections to tricritical scaling.