Origins of magnetic damping measurement variations using ferromagnetic resonance for nano-sized devices

It is shown that ferromagnetic resonance measured in larger thin films yield varying results for damping in nanosized devices. Results are shown to critically depend on magnetic parameters, scalar and vector. Results here also explain why different experiments have concluded different size-dependent trends measuring damping with in-plane devices. The observed variation is due, in part, to a crossover in the dominant eigen-mode and unique eigen-mode evolution. However, antithesizing in-plane devices, we find that for out-of-plane magnetization, distinct symmetric eigen-modes demonstrates ideal stability, leading to no variation in apparent damping, suggesting a better measurement configuration using larger samples.