Quantifying the spin-wave asymmetry in single and double rectangular Ni80_{80}Fe20_{20} microstrips by TR-STXM, FMR and micromagnetic simulations

The asymmetry of spin-wave patterns in confined rectangular Ni$_{80}$Fe$_{20}$ microstrips, both in single and double-strip geometries, is quantified. The results of TR-STXM and micromagnetic simulations are compared. For the TR-STXM measurements and the corresponding simulations the excitation was a uniform microwave field with a fixed frequency of 9.43 GHz, while the external static magnetic field was swept. In the easy axis orientation of the analyzed microstrip, the results show a higher asymmetry for the double microstrip design, indicating an influence of the additional microstrip placed in close proximity to the analyzed one

Three-dimensional spin-wave dynamics, localization and interference in a synthetic antiferromagnet

Spin waves are collective perturbations in the orientation of the magnetic moments in magnetically ordered materials. Their rich phenomenology is intrinsically three dimensional, from the trajectory of the spin precession during their propagation, to the profiles of the spin-wave mode throughout the volume of the magnetic system. This gives rise to novel complex phenomena with high potential for applications in the field of magnonics. However, the three-dimensional imaging of spin waves, key to understanding and harnessing these phenomena, has so far not been possible. Here, we image the three-dimensional dynamics of spin waves excited in a synthetic antiferromagnet, with nanoscale spatial resolution and sub-ns temporal resolution, using time-resolved magnetic laminography. In this way, we map the distribution of the spin-wave modes throughout the volume of the structure, revealing unexpected depth-dependent profiles originating from the interlayer dipolar interaction. We experimentally demonstrate the existence of complex three-dimensional interference patterns, and analyze them via micromagnetic modelling. We find that these patterns are generated by the superposition of spin waves with non-uniform amplitude profiles, and that their features can be controlled by tuning the composition and structure of the magnetic system. Our results open unforeseen possibilities for the study of complex spin-wave modes and their interaction within nanostructures, and for the generation and manipulation of three-dimensional spin-wave landscapes for the design of novel functions in magnonic devices.Comment: 15 pages, 4 figure

Time-of-arrival detection for time-resolved scanning transmission X-ray microscopy imaging

A setup for time-resolved scanning transmission X-ray microscopy imaging is presented, which allows for an increase in the temporal resolution without the requirement of operating the synchrotron light source with low-α optics through the measurement of the time-of-arrival of the X-ray photons. Measurements of two filling patterns in hybrid mode of the Swiss Light Source are presented as a first proof-of-principle and benchmark for the performances of this new setup. From these measurements, a temporal resolution on the order of 20–30 ps could be determined.ISSN:0909-0495ISSN:1600-577

Realization of a magnonic analog adder with frequency-division multiplexing

Being able to accurately control the interaction of spin waves is a crucial challenge for magnonics in order to offer an alternative wave-based computing scheme for certain technological applications. Especially in neural networks and neuromorphic computing, wave-based approaches can offer significant advantages over traditional CMOS-based binary computing schemes with regard to performance and power consumption. In this work, we demonstrate precise modulation of phase- and amplitude-sensitive interference of coherent spin waves in a yttrium-iron-garnet based magnonic analog adder device, while also showing the feasibility of frequency-division multiplexing. Using time-resolved scanning transmission x-ray microscopy, the interference was directly observed, giving an important proof of concept for this kind of analog computing device and its underlying working principle. This constitutes a step toward wave-based analog computing using magnons as an information carrier.ISSN:2158-322