Spin-wave resonance in high-conductivity films: The Fe-Co alloy system

A detailed standing spin-wave resonance (SSWR) study in the frequency range 17-69 GHz in normal and parallel configurations is presented for FexCo1-x alloy films. The implications of the use of different approximate theoretical descriptions for the line positions, widths, and intensities are investigated and compared to the complete theory which includes the coupling of the spin waves to electromagnetic waves by means of the high conductivity of the material. For x=0.55, the exchange parameter A is determined to be 2.7 x 10(-6) erg/cm, i.e., significantly higher than for pure Fe (2.0 x 10(-6) erg/cm). In contrast, the g factor and the damping constant lambda are almost the same for x=0.55 and 1. The problem of interpretation of the surface anisotropy parameter K-s obtained by different experimental methods on different film thicknesses is discussed.