Ferromagnetic resonance in nanostructures with temperature controlled interlayer interaction

The work carries out a comprehensive analysis of magnetic resonance properties of F1/f(d)/F2pin multilayers, where F1 and F2pin are soft and hard magnetic layers and f is a weakly magnetic spacer with the Curie Curie temperature in the vicinity of room temperature. Depending on the magnetic state of the spacer, ferromagnetic or paramagnetic, the exchange interaction between F1 and F2pin becomes a function of temperature which is attractive for a number of applications. Our results show that the interlayer exchange coupling can be enhanced either by decreasing the spacer thickness, d, or lowering temperature. Stronger exchange coupling results in stronger unidirectional anisotropy of the ferromagnetic resonance in F1, as well as in atypical for thin films broadening of the resonance line. The observed behavior was analyzed taking into account two effects of different character - variable spacer thickness d and variable temperature. It is shown that the changes in the unidirectional anisotropy of the FMR spectra have a similar dependence on d and temperature. On the contrary, the FMR line broadening due to magnetization relaxation in the system is significantly affected by the changes in the interlayer exchange interaction on varying d, and is only slightly affected by the changes in temperature.