arXiv subjects

Lorenzo Gnoatto

Publications and source records attributed to Lorenzo Gnoatto.

3 recordsLinked to original sources

arXiv2025

Current-Induced Modulation of Spin-Wave Propagation in a Y-Junction via Transverse Spin-Transfer Torque

We report the transverse control of spin-wave propagation in the configuration where the spin-wave wavevector k is perpendicular to the charge-current density J. Building on theoretical predictions of spin-wave refraction by nonuniform spin-polarized currents, and guided by micromagnetic simulations used to optimize the device geometry and current distribution, we experimentally explore a Y-shaped Permalloy structure in which a locally injected current perturbs the spin-wave dispersion. Measurements reveal current-dependent amplitude differences between the two output branches, providing initial experimental indications consistent with transverse, spin-transfer-torque-driven deflection. Although the magnitude of the effect is modest and accompanied by significant uncertainties, the observed trends qualitatively follow expectations from the simulations. These results demonstrate the feasibility of influencing spin-wave routing through local current injection and establish a proof-of-concept basis for current-controlled manipulation of spin-wave propagation in reconfigurable magnonic circuits.

cond-mat.mes-hall↗

arXiv2025

Controlling Spin-Waves by Inhomogeneous Spin-Transfer Torques

We investigate the interplay between spin currents and spin waves in nanofabricated Permalloy waveguides with geometrical constrictions. Using propagating spin-wave spectroscopy, micromagnetic simulations, and analytical modeling, we provide experimental evidence that spin-wave phase can be modulated by inhomogeneous spin-transfer torques generated by current-density gradients shaped by the constriction geometry. Narrower constrictions enhance these gradients and modify the internal field for Damon-Eshbach spin waves, resulting in pronounced changes in spin-wave group velocity and phase. To our knowledge, this constitutes the first demonstration of deterministic phase modulation via engineered nonuniform spin-transfer torques. Beyond enabling a scalable route to magnonic interferometry - a building block for spin-wave-based computing - our findings establish a platform to control spin-wave dynamics in spatially varying current landscapes, relevant for analogue-gravity experiments in condensed matter systems.

cond-mat.mes-hall↗

arXiv2024

Investigating the Interplay between Spin-Polarization and Magnetic Damping in $\mathrm{Co}_{x}\mathrm{Fe}_{80-x}\mathrm{B}_{20}$ for Magnonics Applications

For magnonics and spintronics applications, the spin polarization ($P$) of a transport current and the magnetic damping ($α$) play a crucial role, e.g. for magnetization dynamics and magnetization switching applications. In particular, $P$ in a glassy (amorphous) 3d transition ferromagnet such as CoFeB and $α$ are both strongly affected by $s-d$ scattering mechanisms. Hence, a correlation can be expected which is a priori difficult to predict. In this work, $P$ and $α$ are measured using current-induced Doppler shifts using propagating spin-wave spectroscopy and broadband ferromagnetic resonance techniques in blanket films and current-carrying $Co_{\rm x}Fe_{\rm {80-x}}B_{\rm 20}$ alloy microstrips. The measured $P$ ranges from 0.18 $\pm$ 0.05 to 0.39 $\pm$ 0.05 and $α$ ranges from $(4.0\pm 0.2)\cdot10^{-3}$ to $(9.7\pm 0.6)\cdot10^{-3}$. We find that for increasing $P$ a systematic drop in $α$ is observed, indicating an interplay between magnetic damping and the spin polarization of the transport current which suggests that interband scattering dominates in $Co_{\rm x}Fe_{\rm {80-x}}B_{\rm 20}$. Our results may guide future experiments, theory, and applications in advancing spintronics and metal magnonics.

physics.app-ph↗