Non-linear parallel pump FMR studies in magnetic insulators*

Non-linear magnetic response of magnetic insulator materials is often used in the realization of radio-frequency (RF) devices. Although in use, there exists physical aspects that still need investigation for such devices. Here, we use high performance parallel computing based CUDA simulations and a theoretical model for magnon scattering to explore the direct and parametric generation of magnons, excited by microwaves in parallel pumped configurations. The sample is 10-100s of um and the response is largely dominated by the demagnetization fields in the sample. The DC applied magnetic field is in-plane and the RF field is linearly polarized and
parallel to the DC field. We first determine the dispersion relation which plays a vital role in the understanding of nonlinear magnons. We then study the effect of ferrimagnet thickness, damping constant, RF frequency and power as well as DC applied magnetic field,
on properties like frequency response, operational bandwidth, and power absorption of the material. It is found that the degree of non-linearity can be controlled using parameters like RF power. Analytically, Holstein and Primakoff based analysis is used to arrive at the threshold RF amplitude and dispersion relations.