Ferromagnetic resonance studies in magnetic nanosystems

This article belongs to the Special Issue Recent Advances in Nanomagnetism.Ferromagnetic resonance is a powerful method for the study of all classes of magnetic materials. The experimental technique has been used for many decades and is based on the excitation of a magnetic spin system via a microwave (or rf) field. While earlier methods were based on the use of a microwave spectrometer, more recent developments have seen the widespread use of the vector network analyzer (VNA), which provides a more versatile measurement system at almost comparable sensitivity. While the former is based on a fixed frequency of excitation, the VNA enables frequency-dependent measurements, allowing more in-depth analysis. We have applied this technique to the study of nanostructured thin films or nanodots and coupled magnetic layer systems comprised of exchange-coupled ferromagnetic layers with in-plane and perpendicular magnetic anisotropies. In the first system, we have investigated the magnetization dynamics in Co/Ag bilayers and nanodots. In the second system, we have studied Permalloy (Ni80Fe20, hereafter Py) thin films coupled via an intervening Al layer of varying thickness to a NdCo film which has perpendicular magnetic anisotropy.D.S.S., D.M. and L.M.Á.-P. acknowledge financial support from the Institut de Physique of CNRS for experimental equipment, a post doc position, and guest researcher stays, respectively. A.H.-R. acknowledges European Union’s Horizon 2020 framework program for research and innovation under the Marie Skłodowska-Curie Action No. H2020-MSCA-IF-2016-746958. A.H.-R., C.Q., J.D. and L.M.Á.-P. would like to thank the Spanish Ministerio de Ciencia e Innovación (MCI) for financial support under Project PID2019-104604RB/AEI/10.13039/501100011033.Peer reviewe