  We describe a minimal model, based on a spin only Hamiltonian with a single
energy scale for itinerant electron metamagnetism. Within this model the
metamagnetic critical field is directly proportional to the temperature where a
peak in the linear susceptibility occurs which in turn is related in a simple
manner to the temperature where the nonlinear susceptibilities also peak. The
spin dependent thermodynamic properties are derived in a straightforward manner
and bear a striking resemblance to observations in such strongly correlated
systems as heavy fermion materials. We also consider extensions of the model by
including effects such as a mean field to encompass observed deviations from a
minimal metamagnetic behavior.
