Rate dependence of first-order reversal curves by using a dynamic Preisach model of hysteresis

First-order reversal curves (FORCs) are used to analyze the kinetic effects described by dynamic Preisach models of hysteresis. It is shown that dynamic processes in magnetic materials strongly affect the symmetry of FORC diagrams. The regions that are most strongly affected when the applied magnetic field varies at high speed are located in the proximity of the diagonal of the FORC diagrams. In these regions, the differential magnetic susceptibility can be negative and result into negative values of the FORC diagrams. An identification technique based on the FORC diagrams is presented for the kinetic parameters of the dynamic Preisach model.