Artist's impression of X-ray Magnetic Vector Chronoscopy (XMVC). A pulsed, polarised X-ray beam (blue) probes a synthetic antiferromagnet: two ultrathin magnetic layers (orange: CoFeB; green: NiFe) separated by a Ru spacer layer, mounted on a microwave waveguide. By recording the full magnetisation vector at successive instances, the technique reconstructs the complete precessional trajectory of the spins in each layer, shown as the orange and green orbits traced on the unit sphere at right.
Researchers at the University of Oxford, Diamond Light Source and ShanghaiTech University developed a new X-ray technique that captures the complete three-dimensional dynamics of coupled magnon modes with unprecedented precision, and for the first time reconstructs their vectorial eigenfunctions in reflection geometry. The findings have been published in Nature Nanotechnology.
Many physical systems are governed by waves, from ripples on water to light and sound. In magnetic materials, the equivalent are collective oscillations of electron spins, known as magnons, which underpin technologies from data storage to next-generation spin-based computing. While the frequencies of these waves are routinely measured, their full motion — how they evolve, rotate, and interact — has until now remained largely hidden.
The new method, called X-ray Magnetic Vector Chronoscopy (XMVC), changes that. By exploiting the pulsed nature of synchrotron X-rays at Diamond Light Source's I10 beamline, the technique stroboscopically films the magnetic dynamics — capturing snapshots of spin motion across an entire oscillation cycle at intervals of a few tens of trillionths of a second. Crucially, by tuning the X-ray energy to specific absorption peaks of chemical elements, the team could isolate and track the motion of individual magnetic layers within a device independently.