Broad-band ferromagnetic resonance characterization of lossy ferromagnetic metallic elements

We developed a method to analyze broad-band ferromagnetic resonance (FMR) data for rectangular ferromagnetic bars of micron and submicron thicknesses. This method allows one to determine the gyromagnetic ratio, the saturation magnetization, and the damping constant of the measured structures. The proposed technique can be used for nondestructive testing of the ferromagnetic elements of micro-electro-mechanical system sensors, actuators, and related devices without any special sample preparation. In the developed approach, an analysis of the FMR linewidth is not needed to determine the damping constant. This method rather utilizes the frequency dependence of the demagnetizing factors in the range of 1–40 GHz for the extraction of magnetic parameters. Its application is demonstrated using Ni81Fe19, Ni45Fe55, and Co35Fe65 specimens as examples.