Mode-Resolved Detection of Magnetization Dynamics Using X-ray Diffractive Ferromagnetic Resonance

Abstract

Collective spin excitations of ordered magnetic structures offer great potential for the development of novel spintronic devices. The present approach relies on micromagnetic models to explain the origins of dynamic modes observed by ferromagnetic resonance (FMR) studies, since experimental tools to directly reveal the origins of the complex dynamic behavior are lacking. Here we demonstrate a new approach which combines resonant magnetic X-ray diffraction with FMR, thereby allowing for a reconstruction of the real-space spin dynamics of the system. This new diffractive FMR technique builds on X-ray detected FMR that allows for element-selective dynamic studies, giving unique access to specific wave components of static and dynamic coupling in magnetic heterostructures. In combination with diffraction, FMR is elevated to the level of a modal spectroscopy technique, potentially opening new pathways for the development of spintronic devices.

Element- and Time-Resolved Measurements of Spin Dynamics Using X-ray Detected Ferromagnetic Resonance

“…Note, however, that XFMR does not provide lateral resolution, so the modal structure of the dynamic magnetic modes remains unexplored. A major breakthrough was recently reported by Burn et al [41] at Diamond Light Source by demonstrating the utilization of a novel diffractive ferromagnetic resonance (DFMR) technique for retrieving the phase-resolved dynamics of [26], and (c-d) is adapted from Q. Li et al [28].…”

X-ray detected ferromagnetic resonance techniques for the study of magnetization dynamics

“…The detection of the X-ray absorption can be done by either X-ray transmission [27,31], fluorescence yield [23], or X-ray scattering or reflectivity [2,35,36,60,61]. However, RF plays havoc with total-electron yield.…”

“…The magnetic resonance modes are probed with linearly polarized light for the range of incident polarization angles η between 0-180 • . (Adapted from Ref [60]…”

“…[60] investigated the complex dynamic behavior of the chiral spin structure in Y-type hexaferrite Ba 2 Mg 2 Fe 12 O 22 .…”

Depth-Resolved Magnetization Dynamics Revealed by X-Ray Reflectometry Ferromagnetic Resonance

“…While FMR only probes the weighted average of the sample response, XFMR can resolve the layer-specific magnetization dynamics in few-layer systems if the layers differ in chemical contrast. Taking advantage of the pulsed time structure of synchrotron radiation, XFMR has been exploited to extract the amplitude and relative phase of precession in individual magnetic layers of spin valve structures [17][18][19] and even on magnetic diffraction peaks [20,21]. However, while XFMR can probe few-layer systems, the depth dependence to the magnetization dynamics from generalized composite materials remains elusive.…”