Random-field effects in metamagnet tricritical-point measurements

It is argued that in metamagnets in finite applied fields, the random fields, both staggered and uniform, generated by the impurity-induced random interactions fundamentally alter the behavior near the tricritical point. As this point is approached along the first-order boundary, two consecutive crossovers are expected, from classical tricriticality to three-dimensional Ising criticality, and then to a rounded transition. This stepwise cross-over occurs asymmetrically in the coexisting phases. These effects are of significant practical importance in many multicritical experiments.