Ferromagnetic Resonance Measurements in Ni–Fe Films from 2–100 Mc/sec

The anisotropy field dispersion in both magnitude and direction has been investigated in Ni–Fe thin films through the frequency range of 2–100 Mc/sec using rf ferromagnetic resonance (FMR). Measurements were centered around the region of field values near Hk where the theory of Smit and Beljers predicts that resonance can be seen at these frequencies. The linewidth measurements as a function of frequency follow a linear relationship which is extrapolated to zero frequency to obtain magnitude dispersion. The slope of this line yields ferromagnetic damping parameters α0 in agreement with Rossing and Nelson. Angular dispersion measurements are obtained by extrapolating a linear relationship between apparent angular dispersion and frequency to zero frequency. Magnitude and angular dispersion measured by ferromagnetic resonance have been compared with measurements of the same quantities using a vibrating sample magnetometer (VSM), and the results are generally in agreement. In addition, the strain dependence of the FMR linewidth has been measured at 2.5 Mc/sec for strains up to 3.4×10−4. A small increase in linewidth with strain has been noted.