Interpretation of magnetisation dynamics using inductive magnetometry in thin films

We present ferromagnetic resonance data from a Py film using both a pulsed inductive microwave magnetometer (PIMM) and conventional FMR. An increase in the damping is seen at low field resonances in the PIMM data from what is expected using conventional FMR. This is explained by the influence of the PIMM's spatially inhomogeneous excitation field and quantified using an intuitive argument. We demonstrate from this derivation how excitation of non-uniform wavevectors can explain the measured increase in damping at low fields observed by the PIMM. We also present results from a coupled Py and Cobalt system, demonstrating that inductive magnetometry can be a sensitive technique for measuring exchange coupling over interfaces and surfaces.