We report on broadband ferromagnetic resonance linewidth measurements performed on epitaxial Heusler thin films. A large and anisotropic two-magnon scattering linewidth broadening is observed for measurements with the magnetization lying in the film plane, while linewidth measurements with the magnetization saturated perpendicular to the sample plane reveal low Gilbert damping constants of (1.5 ± 0.1) × 10 −3 , (1.8 ± 0.2) × 10 −3 , and < 8 × 10 −4 for Co2MnSi/MgO, Co2MnAl/MgO, and Co2FeAl/MgO, respectively. The in-plane measurements are fit to a model combining Gilbert and two-magnon scattering contributions to the linewidth, revealing a characteristic disorder lengthscale of 10-100 nm. arXiv:1909.02738v1 [cond-mat.mtrl-sci]

Magnon scattering enables non-linear microwave devices, such as frequency selective limiters and signal to noise enhancers. It may also impact information transfer within spintronic devices. Here, a quantitative understanding of magnon processes in thin films is developed using micromagnetic simulations, in combination with newly developed analytic theory and experimental data. A technique for calculating the number of magnons at each frequency and wavevector as a function of external input such as power and frequency is identified. It is shown that, near the nonlinear threshold, the dominant parametrically excited magnon pairs are those with minimal group velocity and the correct energy. These results complement Brillouin Light Scattering experiments and indicate a path for wavevector-modulated magnon production based only on simulated results and/or analytic theory, a desirable goal for information transfer and communication.

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