Dynamic Imaging of the Delay- and Tilt-Free Motion of Néel Domain Walls in Perpendicularly Magnetized Superlattices.

We report on the time-resolved investigation of current- and field-induced domain wall motion in the flow regime in perpendicularly magnetized microwires exhibiting antisymmetric exchange interaction by means of scanning transmission X-ray microscopy with a 200 ps time step. The sub-ns time step of the dynamical images allowed us to observe the absence of incubation times for the motion of the domain wall within an uncertainty of 200 ps, together with indications for a negligible inertia of the domain wall. Furthermore, we observed that, for short current and magnetic field pulses, the magnetic domain walls do not exhibit a tilting during their motion, providing a mechanism for the fast, tilt-free, current-induced motion of magnetic domain walls.

Strain-Tuned Spin-Wave Interference in Micro- and Nanoscale Magnonic Interferometers.

Here, we report on the experimental study of spin-wave propagation and interaction in the double-branched Mach-Zehnder interferometer (MZI) scheme. We show that the use of a piezoelectric plate (PP) with separated electrodes connected to each branch of the MZI leads to the tunable interference of the spin-wave signal at the output section. Using a finite element method, we carry out a physical investigation of the mechanisms of the impact of distributed deformations on the magnetic properties of YIG film. Micromagnetic simulations and finite-element modelling can explain the evolution of spin-wave interference patterns under strain induced via the application of an electric field to PP electrodes. We show how the multimode regime of spin-wave propagation is used in the interferometry scheme and how scaling to the nanometer size represents an important step towards a single-mode regime. Our findings provide a simple solution for the creation of tunable spin-wave interferometers for the magnonic logic paradigm.

Diameter-independent skyrmion Hall angle observed in chiral magnetic multilayers.

Magnetic skyrmions are topologically non-trivial nanoscale objects. Their topology, which originates in their chiral domain wall winding, governs their unique response to a motion-inducing force. When subjected to an electrical current, the chiral winding of the spin texture leads to a deflection of the skyrmion trajectory, characterised by an angle with respect to the applied force direction. This skyrmion Hall angle is predicted to be skyrmion diameter-dependent. In contrast, our experimental study finds that the skyrmion Hall angle is diameter-independent for skyrmions with diameters ranging from 35 to 825 nm. At an average velocity of 6 ± 1 ms-1, the average skyrmion Hall angle was measured to be 9° ± 2°. In fact, the skyrmion dynamics is dominated by the local energy landscape such as materials defects and the local magnetic configuration.

Elastic wave propagation in a microstructured acoustic fiber.

Elastic wave propagation along the structure of hollow cylinders in a linear isotropic medium is investigated. The multipole method for modeling elastic waves propagation in such structures is formulated and implemented. Using the multipole method, dispersion dependencies of the structures (microstructured fibers) containing 3, 6, and 7 hollow cylinders are calculated. Comparison with wave dispersion properties along one cylinder is made. Also, an approximate physical model based on an equivalent coaxial waveguide and multipole method is proposed. Exploiting this model, wave dispersion of the wave propagating along a structure with 18 hollow cylinders is calculated. Validation of the model is also proposed.