Magnetization and ferromagnetic resonance in a Fe/Gd multilayer: experiment and modelling

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism

Background:

• Superlattices composed of alternating magnetic layers, such as iron (Fe) and gadolinium (Gd), exhibit unique magnetic behaviors.
• Understanding the interplay between static and dynamic magnetic properties is essential for developing novel magnetic materials and devices.

Purpose of the Study:

• To experimentally investigate the static and dynamic magnetic properties of [Fe(35 Å)/Gd(50 Å)]12 superlattices.
• To theoretically model the observed magnetic behavior using numerical simulations based on the effective field model.

Main Methods:

• SQUID magnetometry was used to measure static magnetic properties.
• Ferromagnetic resonance (FMR) technique at frequencies ranging from 7 to 38 GHz was employed to study dynamic magnetic properties.
• Numerical simulations based on the effective field model, incorporating Gilbert damping and a non-local diffusion-type absorption term, were used for theoretical analysis.

Main Results:

• Experimental magnetization curves and FMR spectra were well-approximated by the effective field model at all measured temperatures (5-295 K).
• A significant temperature dependence of the effective field parameter in gadolinium layers was necessary for accurate agreement with experimental data.
• A non-local diffusion-type absorption term, in addition to Gilbert damping, was required to explain the specific features observed in the FMR spectra.

Conclusions:

• The effective field model, with temperature-dependent parameters and an additional non-local absorption term, successfully describes the static and dynamic magnetic properties of Fe/Gd superlattices.
• The findings highlight the importance of considering temperature effects and non-local phenomena in understanding the magnetic behavior of multilayered magnetic systems.