The FMR linewidth and its anisotropy in F1/f/F2/AF multilayers, where spacer f has a low Curie point compared to the strongly ferromagnetic F1 and F2, is investigated. The role of the interlayer exchange coupling in magnetization relaxation is determined experimentally by varying the thickness of the spacer. It is shown that stronger interlayer coupling via thinner spacers enhances the microwave energy exchange between the outer ferromagnetic layers, with the magnetization of F2 exchange-dragged by the resonance precession in F1. A weaker mirror effect is also observed: the magnetization of F1 can be exchange-dragged by the precession in F2, which leads to anti-damping and narrower FMR linewidths. A theory is developed to model the measured data, which allows separating various contributions to the magnetic relaxation in the system. Key physical parameters, such as the interlayer coupling constant, in-plane anisotropy of the FMR linewidth, dispersion of the magnetic anisotropy fields are quantified. These results should be useful for designing high-speed magnetic nanodevices based on thermally-assisted switching.
@article{arxiv.1604.05145,
title = {Anisotropic magnetization relaxation in ferromagnetic multilayers with variable interlayer exchange coupling},
author = {A. F. Kravets and D. M. Polishchuk and Yu. I. Dzhezherya and A. I. Tovstolytkin and V. O. Golub and V. Korenivski},
journal= {arXiv preprint arXiv:1604.05145},
year = {2016}
}