8.

Title: Would Magnonic Circuits Outperform CMOS Counterparts?
Authors: A. Mahmoud, N. Cucu-Laurenciu, F. Vanderveken, F. Ciubotaru, C. Adelmann, S. Cotofana, and S. Hamdioui
Preprint: arXiv:2204.10732

 7.

Title: Theoretical description of power transfer in a magneto-acoustic resonator
Authors: Frederic Vanderveken, Bart Soree, Florin Ciubotaru, Christoph Adelmann
Preprint: arXiv:2204.03072

 6.

Title: A GHz operating ScAlN based SAW resonator used for Surface Acoustic Waves/Spin Waves Coupling
Authors: I. Zdru, C. Nastase, L. N. Hess, F. Ciubotaru, A. Nicoloiu, D. Vasilache, M. Dekkers, M. Geilen, C. Ciornei, A. Dinescu, C. Adelmann, M. Weiler, P. Pirro and A. Müller
Preprint: 10.36227/techrxiv.19486781.v1

 5.

Title: Measuring a population of spin waves from the electrical noise of an inductively coupled antenna
Authors: T. Devolder, S.-M. Ngom, A. Mouhoub, J. Letang, J.-V. Kim, P. Crozat, C. Chappert, J.-P. Adam, A. Solignac
Preprint: arXiv:2204.01427

 4.

Title: Parametric excitation and instabilities of spin waves driven by surface acoustic waves
Authors: M. Geilen, A. Nicoloiu, D. Narducci, M. Mohseni, M. Bechberger, M. Ender, F. Ciubotaru, A. Müller, B. Hillebrands, C. Adelmann, and P. Pirro
Preprint: arXiv:2201.04033

 3.

Title: Spin wave based approximate 4:2 compressor
Authors: A. Mahmoud, F. Vanderveken, F. Ciubotaru, C. Adelmann, S. Hamdioui, and S. Cotofana
Preprint: arXiv:2109.09554

 2.

Title: Spin wave based 4:2 compressor
Authors: A. Mahmoud, F. Vanderveken, F. Ciubotaru, C. Adelmann, S. Hamdioui, and S. Cotofana
Preprint: arXiv:2109.09516

 1.

Title: Fully resonant magnetoelastic spin wave excitation by surface acoustic waves under conservation of energy and linear momentum
Authors: M. Geilen, A. Nicoloiu, D. Narducci, M. Mohseni, M. Bechberger, M. Ender, F. Ciubotaru, A. Müller, B. Hillebrands, C. Adelmann, and P. Pirro
Preprint: arXiv:2106.14705

For many years, the research has been based in finding alternative computing paradigms beyond the CMOS horizon to further improve computational platforms. Among all beyond-CMOS approaches, spintronics has been identified as particularly promising due to the low intrinsic energies of magnetic excitation as well as their collective nature.

A group of disruptive spintronic devices concepts have been based on spin waves as information carriers. Spin waves are oscillatory collective excitations of the magnetic moments in ferromagnetic or antiferromagnetic media.

Of crucial importance in spin-waves devices and circuits are the waveguide structures. In waveguides with dimensions comparable or smaller than the wavelength, the dispersion relation of spin waves is strongly affected by waveguide boundaries and lateral confinement effects. In general, the dispersion relation of long-wavelength dipolar spin waves depends on the direction of the wavevector and the static magnetization. There are three limiting cases of dipolar spin waves, often called surface spin waves (SSW), forward volume waves (FVSW) and backward volume waves (BVSW) (details: Mahmoud et al., J. Appl. Phys. 128, 161101 (2020))

In absence of nonlinear effect, the interaction of coherent waves is described by interference, i.e. the addition of their respective amplitudes at each point in space and time.

For in-phase waves with equal frequency, constructive interference leads to a peak-to-peak amplitude of the generated wave that is equal to the sum of the peak-to-peak amplitudes of the input waves. By contrast, destructive interference leads to a subtraction of the peak-to-peak amplitudes of input waves when their phase difference is π.

Magnetoelectrics are a class of spintronic materials that have received particular attention due to their potential to manipulate magnets at very low power and the possibility for new functionalities. Besides multiferroic materials, which possess simultaneous magnetic and ferroelectric polarization, magnetoelectric composites have been at the center of research on magnetoelectricity for decades. Such composites consist of piezoelectric and magnetostrictive materials and rely on the interaction between the magnetization and mechanical degrees of freedom.

Applying an electric field to a piezoelectric material leads to the generation of a mechanical deformation (strain) that can be transferred to an adjacent magnetostrictive material. The strain inside the (ferromagnetic) magnetostrictive material leads then to a magnetoelastic effective magnetic field via the Villari effect (inverse magnetostriction) that can exert a torque on the magnetization. Conversely, the rotation of the magnetization in a magnetostrictive material generates strain that can lead to charge separation and an electric polarization in an adjacent piezoelectric material.

Of particular interest was the geometry of the transducer and the impact of the non-active surrounding layers on the effective magnetoelastic and magnetoelectric coupling. The “active” part of the structure consisted of a pillar including the magnetoelectric bilayer and two metal electrodes.

In the same way, the experimental device structure is based on a magnetoelectric pillar transducer. Functional ME spin wave transducers down to 500 nm CD and up to 10 GHz has already been demonstrated.

Our implementation will be based on Co₄₀Fe₄₀B₂₀ and permalloy waveguides with widths down to 850 nm. 

Micromagnetic simulations for 850-nm-wide Co₄₀Fe₄₀B₂₀ waveguides in the Damon-Eshbach geometry show the excitation of spin waves confined in the center of the waveguide.

Animations of the experimental magnetization dynamics in a SWMG with a 2.0 μm wide permalloy waveguide, imaged by time-resolved scanning transmission x-ray microscopy for different combinations of input phases: (π; π; π); (0; 0; π); (0; π; 0). The input phase combinations are indicated in the animations (details: Talmelli et al, Sci. Adv. 6(51), eabb4042 (2020)).

Animations of the magnetization dynamics in a SWMG with an 850 nm wide Co₄₀Fe₄₀B₂₀ waveguide calculated by micromagnetic simulations for different combinations of input phases: (0; 0; 0); (π; 0; π). The input phase combinations are indicated in the animations. The complementary combinations (π; π; π) and (0; π; 0) can be obtained by shifting the time by half of a period.