| Nanocomposite films comprising Fe grains in a non-magnetic oxide matrix are of interest due to potential applications in high-frequency circuits. The small Fe grain size leads to an effective averaging of magneto-crystalline anisotropy, leading to soft magnetic properties. The high saturation magnetization (MS) of the Fe leads to high permeabilities, while the high resistance of the oxide matrix precludes eddy current damping at high frequencies. In the gyromagnetic frequency regime the domain wall motion is expected to be severely damped, allowing only coherent rotation. For systems with coherent rotation being the only mode of reversal, the permeability is governed by the Snoek Limit.; This dissertation examines the effect of the Fe grain size and volume fraction on the gyromagnetic properties of Fe-R-O soft magnetic films. The nanocomposite and therefore magnetically inhomogeneous nature of the system presents a challenge in terms of the determination of the local magnetic properties. Various experimental techniques are used for DC and high frequency characterization. The local MS values, obtained from FMR measurements, show a distinct dependency on the surface to volume ratio. The large deviation from Snoek behavior is attributed to domain wall effect. |
