Theory of itinerant-electron metamagnetism: II. The origin of the susceptibility maximum

We give a theoretical explanation for the phenomenon of the magnetic susceptibility showing a maximum at low temperature T-m for those compounds that show itinerant-electron metamagnetism. We also derive the linear relation between the metamagnetic transition field H-m and T-m observed experimentally for Y(Co1-xAlx)(2), paying particular attention to the effects of the zero-point quantum spin fluctuations and assuming the existence of almost energetically degenerate paramagnetic thermodynamic states.