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.