arXiv subjects

Alexandre Abbass Hamadeh

Publications and source records attributed to Alexandre Abbass Hamadeh.

4 recordsLinked to original sources

arXiv2026

Resonant excitations via low frequency pumping in driven magnon systems

We analyse resonant excitations of ferromagnetic magnons via microwave pumping using Floquet theory. Special focus is put on driving frequencies that are below the corresponding magnon energy, which can be excited in large parameter regions via parametric resonances. We develop a theoretical framework that analytically predicts the regions of resonances and resonance thresholds in thin films of ferro- and ferri-magnetic materials like YIG as a function of damping, amplitude and frequency. Resonance regions are separated by exceptional points of the quasi-energies and the results are compared with micromagnetic simulations. The corresponding threshold amplitudes can be estimated from a characteristic powerlaw with damping, leading to the possibility of targeted exciatations at selected wavenumbers using low frequency drive.

cond-mat.mes-hall↗

arXiv2026

Spin-wave phase modulation using magnetic domain walls in dipolarly coupled structures for non-volatile magnonic computation

A controllable phase shifter is a key component for spin-wave-based logic and information processing devices. Here, we propose a domain-wall-position-controlled spin-wave phase shifter that exploits dipolar coupling between two closely spaced waveguides to enable continuous phase tuning over a range approaching 360degrees while keeping the spin-wave amplitude constant. Using micromagnetic simulations, we model a bias-free hybrid structure composed of a nanoscale waveguide magnetostatically coupled to a half-ring-shaped structure both made from bismuth-doped yttrium iron garnet with strong perpendicular magnetic anisotropy. Displacing a domain wall in the half-ring modulates the dispersion relation in the adjacent straight waveguide due to the changed magnetostatic interaction, providing a compact and dynamically reconfigurable phase-shifting mechanism. This approach offers precise and non-volatile control over spin-wave propagation and is compatible with energy-efficient magnonic logic architectures.

cond-mat.mes-hall↗

arXiv2026

An all-magnonic neuron with tunable fading memory

Magnonics offers nanometer-scale wave propagation and strong nonlinearities, making it attractive for neuromorphic applications such as artificial neurons. Yet, magnonic elements with interconnections solely within the magnonic system remain challenging, preventing the realization of interconnected magnonic neurons to date. Here, we experimentally demonstrate an all-magnonic neuron that reacts to magnon inputs with thresholded, amplified magnon firing and subsequent self-reset, enabling all-magnonic operation and cascading. Our approach is based on micro-antenna excitation on an ultra-low damping garnet with perpendicular magnetic anisotropy (PMA), where we exploit the positive magnon frequency shift to realize nonlinear activation. Using Brillouin light scattering spectroscopy, we uncover a transient neuron response with tunable fading memory: A 25% change in pump power results in a 3-order-of-magnitude tuning in memory time, which we harness, demonstrating temporal integration of up to 50 magnon pulses. Finally, we realize neuron triggering in a cascade of 3 neurons, highlighting its potential for connected magnonic circuits.

cond-mat.mtrl-sci↗

arXiv2025

Ratchet motion of magnetic skyrmions driven by surface acoustic sawtooth waves

The manipulation of skyrmions by surface acoustic waves (SAW) has garnered significant interest in the field of spintronic devices. Previous studies established that skyrmions can be generated and moved by strain pulses. In this study, we propose that sawtooth-SAWs can be used to drive a ratchet motion of magnetic skyrmions in the presence of pinning centers. This results in a net motion of the skyrmions orthogonal to the continuously applied SAW. The ratchet motion is fundamentally caused by non-vanishing pinning, so that a certain strain gradient magnitude is required to overcome pinning and start skyrmion motion. We demonstrate the feasibility of our concept by micromagnetic simulations and analytical model calculations.

cond-mat.mes-hall↗