Magnetic Resonance Properties of Thin Py Films Suitable for Excitation of Spin Waves.

Low magnetic damping and narrow ferromagnetic resonance (FMR) linewidth are essential for efficient spin-wave excitation in magnonic devices. We investigate how a combination of deposition techniques, interface engineering, and consequent thermal treatment affects magnetic losses in thin permalloy (Py, Ni80Fe20) films prepared by electron-beam evaporation and magnetron sputtering. Broadband vector network analyzer FMR, atomic force microscopy, and electromagnetic simulations were used to correlate linewidth, surface morphology, and spin-wave excitation. Comparable minimum linewidths were reached by both deposition routes: approximately 23 Oe at 4 GHz for the best electron-beam-evaporated film and approximately 21 Oe for a 20 nm TaN/Py/TaN structure. Electron-beam-evaporated films proved sensitive to substrate choice, surface preparation and-in the absence of plasma cleaning-deposition temperature, whereas the magnetic field applied during growth had only a weak effect. After magnetic annealing, however, only the TaN-encapsulated structure retained its narrow linewidth, while the uncapped films broadened substantially. Simulations further showed that linewidth reduction enhances the excitation efficiency and visibility of standing spin-wave modes. These results indicate that comparable losses are achievable through several process routes, whereas retaining them through thermal processing requires interface engineering-a distinction that matters for integrating Py films into magnonic and spintronic devices.