Spin dynamics in a Curie-switch

Ferromagnetic resonance properties of F${}_1$/f/F${}_2$/AF multilayers, where weakly ferromagnetic spacer f is sandwiched between strongly ferromagnetic layers F${}_1$ and F${}_2$, with F${}_1$ being magnetically soft and F${}_2$ - magnetically hard due to exchange pinning to antiferromagnetic layer AF, are investigated. Spacer-mediated exchange coupling is shown to strongly affect the resonance fields of both F${}_1$ and F${}_2$ layers. Our theoretical calculations as well as measurements show that the key magnetic parameters of the spacer, which govern the ferromagnetic resonance in F${}_1$/f/F${}_2$/AF, are the magnetic exchange length ($\mathrm{\Lambda }$), effective saturation magnetization at $T=0$ $(m_0)$, and effective Curie temperature ($T_{\text{C}}^{\text{eff}}$). The values of these key parameters are deduced from the experimental data for multilayers with f = Ni${}_x$Cu${}_{100-x}$, for the key ranges in Ni-concentration ($x=54÷70$ at. %) and spacer thickness ($d=3÷6$ nm). The results obtained provide a deeper insight into thermally-controlled spin precession and switching in magnetic nanostructures, with potential applications in spin-based oscillators and memory devices.