Numerical investigation of the surface impedance of ferromagnetic manganite thin films

The surface impedance and the microwave characteristics of conductive ferromagnetic (FM) films with the parameters similar to those of La0.7Sr0.3MnO3 (LSMO) films deposited on a dielectric substrate were modeled with respect to linearly polarized planar transverse electromagnetic waves, incident normally to the structure. It was shown that the microwave losses caused by the film conductivity dominate the losses due to the ferromagnetic resonance (FMR) if the film is thin enough. The FMR is more clearly observed in FM films deposited on substrates of higher permittivity due to smaller microwave losses, caused by the film conductivity in this case. The peculiarities of the surface impedance and the absorption, reflection and transmission coefficients caused by the film conductivity and FMR are simultaneously observed in thicker films.