Field-dependent susceptibility of a paramagnet

The physical orign of peaks observed in the field-dependent susceptibility of a number of ferromagnets at temperatures above the critical temperature Tc is identified. As a corollary it is shown that the field-dependent susceptibility of a paramagnet exhibits an obvious but little discussed structure at finite temperature, of similar origin. This structrure can be used to extract information on the zero-temperature transition that should occur in paramagnetic systems (systems which, formally, do not experience any interactions), in a manner similar to that used to extract information on the finite-temperature phase transition in ferromagnets. This provides strong confirmatory evidence that this type of anomaly is static rather than dynamic in origin.