Knowledge Bank

A ferromagnetic spin wave spectrum from an annealed FeTaN thin film was observed in a spectrometer operating at 34.5 GHz. This spectrum was not observed in an unannealed film. Six different absorption lines were measured as a function of magnetic field, and a plot of the square of the spin wave number against the resonance field value yields a straight line whose slope can be related by theory to an exchange coupling constant of $1.7\times 10-6$ ergs/cm. These results indicate that pinning is occurring at only one of the film interfaces, annealing causes the magnetic interface properties to change and produce pinning, and the exchange coupling constant value compares well with reported values of $Fe1$, $NiFe2$ and $FeAIN3$ films. The spin-wave theory describing the above linear relationship and the significance of these results to ferromagnetic film preparation will be discussed.