Quantifying the Spin-Wave Asymmetry in Single and Double Rectangular Ni80Fe20 Microstrips by TR-STXM, FMR, and Micromagnetic Simulations

The asymmetry of spin-wave (SW) patterns in confined rectangular Ni80Fe20 microstrips, both in single- and double-strip geometries, is quantified. The results of time-resolved scanning transmission X-ray microscopy (TR-STXM) and micromagnetic simulations are compared. For the TR-STXM measurements and the corresponding simulations, the excitation was a uniform microwave (MW) field with a fixed frequency of 9.43 GHz, while the external static magnetic field was swept. In the easy axis orientation of the analyzed microstrip, the results show a higher asymmetry for the double microstrip design, indicating an influence of the additional microstrip placed in close proximity to the analyzed one. Index Terms— Ferromagnetic resonance (FMR), magnonics, micromagnetics, mumax3, spin waves (SWs), SW imaging, SW sym- metry, time-resolved scanning transmission X-ray microscopy (TR-STXM).