Spin dynamics in a Curie-switch

TL;DR

This study investigates how a weakly ferromagnetic spacer influences spin dynamics in multilayer structures, revealing key parameters that control ferromagnetic resonance and potential for thermally-controlled spin devices.

Contribution

The paper identifies the main magnetic parameters governing resonance in F$_1$/f/F$_2$/AF multilayers and provides experimental values for NiCu spacers across various compositions and thicknesses.

Findings

Spacer-mediated exchange coupling affects resonance fields.

Key parameters include exchange length, saturation magnetization, and Curie temperature.

Experimental data deduces these parameters for NiCu spacers.

Abstract

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 ($\Lambda$), 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 ($x=54\div70$ at. %) and spacer thickness ($d=3\div 6$ 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.