A study of rf nonlinearities in nickel

A new and very sensitive method (1 part in 1019) for studying nonlinear properties of metallic systems under the influence of radio-frequency fields is described. The method is applied to a study of the intermodulation generation at 150 MHz in nickel as a function of a dc field and as a function of the power of the two simultaneously applied rf fields at 146 and 148 MHz. As the dc field is increased for a given applied rf power, the intermodulation signal shows a number of linear regions of decrease on a semilogarithmic graph. Different results are obtained which depend on the relative orientations of the dc and rf magnetic fields. The power of the intermodulation signal shows a cubic or quadratic dependence on the power of the applied rf fields for low or high values of the dc field, respectively. These results are discussed in terms of the interaction of the rf field with the domain walls using a recent model of an electroplated nickel domain structure proposed by others.