ESR study of hard/soft (Sm-Co/Fe) magnetic film: model exchange - spring magnetic multilayer samples

Electron spin resonance (ESR) measurements were carried out on Fe /SmCo magnetic film. The ESR spectra have been taken for both parallel geometry (where the applied magnetic field is in the film plane) and perpendicular geometry ( the applied magnetic field is perpendicular to the film plane). The magnetic films were devided into sub-layers which are consist of a single atomic layers with an average magnetization Mi .The spins in each layers are characterized by an uniaxial anisotropy constant Ki and make an angle of θi with respect to the applied filed in sample plane. The spins in adjacent layers are seperated by a distance of d=2A''0 and they are coupled by an exchange constant Ai,i+1. The total energy are assumed to contains Zeeman, exhange and anisotropy constributions. Thus equilibrium spin direction θ''i''' were calculated by using minimum energy condition dE/dθi =0... The resonance relation of each layer are derived from the total energy function with equilibrium value θ and Φ by using the Landau-Lifshitz dynamic equation of motion for magnetization in spherical coordinates. Hence the simulated ESR absorption spectra are obtained by using the above procedure in a computer programme