Experimental Test of the Smoothness Hypothesis inCsCoCl3· 2D2O

Here the results are reported of a neutron-diffraction study of the critical behavior of $M$ and $M_{\mathrm{s}\mathrm{t}}$ along the line of critical points in the magnetic phase diagram of the metamagnet ${\mathrm{CsCoCl}}_3$ · 2${\mathrm{D}}_2$O. It is shown that the critical behavior of $M$ and $M_{\mathrm{s}\mathrm{t}}$ can each be represented by a single critical exponent up to the multicritical point, where a breakdown of smoothness and crossover is observed.