Spin wave resonance in thin films and in bulk samples of FeNi invar alloys

Abstract The spin wave resonance (SWR) at 9.2 GHz has been investigated in single layer films ( d ⋍200 nm) and multi layer films of FeNi. The variation of the spin wave parameters as a function of Ni concentration is determined at room temperature. For a Fe 20 Ni 80 single layer and a Fe 65 Ni 35 multi layer the temperature dependence has been studied in the range of 4 to 300 K. Besides, the SWR has been measured in annealed bulk samples of Fe 63 Ni 37 at 9.2 and 33.8 GHz as a function of temperature. From the SWR spectra of the bulk and film samples quantitative values of the effective magnetization, the g factor, and the exchange stiffness parameter have been determined.