Dispersion Relations for Nonlinear Response

Abstract

A class of dispersion relations for quadratic response is discussed. An experimental verification of these relations for magnetic systems is suggested. In a typical experiment there are two parallel high-frequency magnetic fields, perpendicular to a constant field. The response in the direction of the constant field has five components, corresponding with the sum and the difference of the frequencies of the perturbing fields, twice these frequencies, and frequency zero. The dispersion relations are integral relations for the corresponding susceptibilities. In a final section an integral relation connecting the second-order response with a component of the linear susceptibility tensor is formulated.