Magnetic resonances and microwave permeability in thin Fe films on flexible polymer substrates

Ferromagnetic resonance (FMR) and coaxial line techniques are employed for studying the high-frequency magnetic properties of thin Fe films deposited onto a flexible polymer substrate by magnetron sputtering. Multiple resonances are observed in the FMR spectra measured in X frequency range for films with thickness from 0.1 to 2.0 μm. The resonance magnetic fields are found to depend on of the film thickness and on the orientation of external magnetic field relative to the film plane. The variation of the FMR parameters with the layer thickness may be attributed to differences in the shape and size of nanocrystallites formed during the deposition of films of different thicknesses. Low-field resonance modes are found in addition to the homogeneous FMR of saturated magnetization. Qualitative agreement is observed between values of the resonance magnetic fields determined by FMR and coaxial line techniques.