Nonlinear Parallel-Pumped FMR: Three and Four Magnon Processes

• Published in: IEEE transactions on microwave theory and techniques Vol. 68; no. 2; pp. 602 - 610
• Main Authors: Venugopal, Aneesh, Qu, Tao, Victora, R. H.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Computer simulation; Ferromagnetic resonance (FMR); Ferromagnetism; frequency-selective limiters (FSLs); Graphics processing units; Magnetic materials; Magnetic resonance; Magnetic thin films; Magnetomechanical effects; Magnetostatics; magnon; Magnons; Micromagnetics; Microwave frequencies; Nonlinear response; Nonlinearity; parallel pump; parametric pumping; Predictions; Radio frequency; Saturation magnetization; Scattering; spin waves; Thin films; Variations; yttrium iron garnet (YIG)
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2019.2952128

The nonlinear response of a magnetic thin film subject to microwave radiation is quantitatively predicted in the steady state. Three- and four-magnon processes are shown to cause this nonlinearity with a strong dependence on magnetic bias field, microwave frequency, and applied power. Predictions are calculated using large-scale micromagnetic simulations executed on graphics processing units (GPUs) and include thermal fluctuations. A 2-D simulation paradigm is proposed for reducing the resource requirements while being able to capture the qualitative and quantitative behavior of the significant microwave-ferromagnet interactions in the parallel pumping configuration. A mathematical formalism specific to thin films is then developed to explain the aforementioned behavior of such magnetic materials based on their predicted magnon dispersion relation. The simulated predictions for high-power (nonlinear) performance are in close agreement with experiment even though the material parameters are only taken from low-power (linear) data.