Effect of external factors on the ferromagnetic resonance line width in exchange-biased structures

The external factors which influence the ferromagnetic resonance (FMR) line width in bilayer (ferromagnet/antiferromagnet) exchange-biased systems are studied. The dependence of the FMR line width on the antiferromagnetic (AF) layer thickness at a constant ferromagnet (FM) layer thickness are studied for the samples with various sequences of deposition of FM and AFM layers; the correlations between the exchange-bias field and the roughness of the sample surface are studied, too. The exchange bias is found to give insignificant contribution to the FMR line width. In the systems with an antiferromagnet deposited on a ferromagnetic layer, the FMR line width increases proportionally to the average surface roughness size. In the system with inverse arrangement of the layers, the uniaxial anisotropy gives a significant contribution to the line width. The FMR line width is in the quadratic dependence on the uniaxial anisotropy and is inversely proportional to the AFM layer thickness, which can be related to changes in the microstructure with the thickness as an external factor of damping FMR.