arXiv subjects

Andrea Mucchietto

Publications and source records attributed to Andrea Mucchietto.

8 recordsLinked to original sources

arXiv2026

Soft-X-ray momentum microscopy of nonlinear magnon interactions below 100-nm wavelength

Magnons are quantised collective excitations of long-range ordered spins. At nanometre wavelengths, exchange interactions increasingly govern their dynamics, giving rise to a largely unexplored regime of couplings between magnons and other quasiparticles. Yet, detecting such short-wavelength spin waves has remained a key experimental challenge. Here, we introduce Magnon Momentum Microscopy (MMM) -- a quasi-elastic, resonant magnetic soft-X-ray scattering technique that directly images magnon populations across two-dimensional momentum space. Owing to its remarkable sensitivity, MMM can capture nonlinear magnon-magnon interactions over large regions of the dispersion plane. Applying MMM to the prototypical magnonic material yttrium iron garnet (YIG), we uncover a rich variety of previously unobserved nonlinear magnon interactions. With its element specificity, bulk sensitivity, as well as intrinsic access to nanometre-scale wavelengths without frequency limitation, soft-X-ray MMM establishes a powerful and versatile platform for exploring short-wavelength and nonlinear magnonics.

cond-mat.mes-hall↗

arXiv2025

A scalable photonic quantum interconnect platform

Many quantum networking applications require efficient photonic interfaces to quantum memories which can be produced at scale and with high yield. Synthetic diamond offers unique potential for the implementation of this technology as it hosts color centers which retain coherent optical interfaces and long spin coherence times in nanophotonic structures. Here, we report a technique enabling wafer-scale processing of thin-film diamond that combines ion implantation and membrane liftoff, high-quality overgrowth, targeted color center implantation, and serial, high-throughput thermocompression bonding with yields approaching unity. The deterministic deposition of thin diamond membranes onto semiconductor substrates facilitates consistent integration of photonic crystal cavities with silicon-vacancy (SiV) quantum memories. We demonstrate reliable, strong coupling of SiVs to photons with cooperativities approaching 100. Furthermore, we show that photonic crystal cavities can be reliably fabricated across several membranes bonded to the same handling chip. Our platform enables modular fabrication where the photonic layer can be integrated with functionalized substrates featuring electronic control lines such as coplanar waveguides for microwave delivery. Finally, we implement passive optical packaging with sub-decibel insertion loss. Together, these advances pave the way to the scalable assembly of optically addressable quantum memory arrays which are a key building block for modular photonic quantum interconnects.

quant-ph↗

arXiv2025

Tunable magnon emission from a nano-optomagnet

The growing demand for dense, energy-efficient, and high-frequency signal processing continues to drive device miniaturization. While downscaling remains a central challenge, magnons offer a promising solution as nanoscale signal carriers, supporting broadband operation from GHz to THz without moving charge carriers and generating Joule heating. However, their integration at the nanoscale is limited by conventional electrical excitation based on coplanar waveguides, which require metal pads few to hundreds of micrometres in size. Here, we demonstrate tunable magnon emission into a yttrium iron garnet film by focusing microwave-modulated laser light onto an integrated Au nanodisc. Using inelastic light scattering spectroscopy, we observe magnons whose frequencies match the optical modulation frequencies in the GHz frequency regime. The largest magnon amplitudes are found for circularly polarized laser light and specific nanodisc diameters consistent with a plasmon-enhanced inverse Faraday effect. These results establish plasmonic nanoantennas as reconfigurable nanoscale magnon sources, enabling broadband signal generation governed entirely by optical modulation.

physics.optics↗

arXiv2023

Magnon-assisted magnetization reversal of Ni81Fe19 nanostripes on Y3Fe5O12 with different interfaces

Magnetic bit writing by short-wave magnons without conversion to the electrical domain is expected to be a game-changer for in-memory computing architectures. Recently, the reversal of nanomagnets by propagating magnons was demonstrated. However, experiments have not yet explored different wavelengths and the nonlinear excitation regime of magnons required for computational tasks. We report on the magnetization reversal of individual 20-nm-thick Ni81Fe19 (Py) nanostripes integrated onto 113-nm-thick yttrium iron garnet (YIG). We suppress direct interlayer exchange coupling by an intermediate layer such as Cu and SiO2. Exciting magnons in YIG with wavelengths λ down to 148 nm we observe the reversal of the integrated ferromagnets in a small opposing field of 14 mT. Magnons with a small wavelength of λ = 195 nm, i.e., twice the width of the Py nanostripes, induced the reversal at an unprecedentedly small spin precessional power of about 1 nW after propagating over 15 μm in YIG. Considerations based on dynamic dipolar coupling explain the observed wavelength dependence of magnon-induced reversal efficiency. For an increased power the stripes reversed in an opposing field of only about 1 mT. Our findings are important for the practical implementation of nonvolatile storage of broadband magnon signals in YIG by means of bistable nanomagnets without the need of an appreciable global magnetic field.

cond-mat.mes-hall↗

arXiv2023

Magnetization Reversal of 50-nm-wide Ni81Fe19 Nanostripes by Ultrashort Magnons in Yttrium Iron Garnet for Memory-Enhanced Magnonic Circuits

Spin waves (magnons) can enable wave-based neuromorphic computing by which one aims at overcoming limitations inherent to conventional electronics and the von Neumann architecture. In this study, we explore the storage of magnon signals and the magnetization switching of periodic and aperiodic arrays of Ni81Fe19 (Py) nanostripes with widths (w) between 50 nm and 200 nm. Spin waves excited with low microwave power in yttrium iron garnet induce the reversal of the nanostripes of different w in a small opposing field. Exploiting microwave-to-magnon transducers for magnon modes with ultrashort wavelengths, we demonstrate the reversal of 50-nm-wide Py nanostripes by magnons with wavelength ~ 100 nm after they have propagated over 25 micrometer in YIG. The findings are important for designing a magnon-based in-memory computing device.

cond-mat.mes-hall↗

arXiv2023

Nonreciprocal Spin Waves in Nanoscale Domain Walls Detected by Scanning X-ray Microscopy in Perpendicular Magnetic Anisotropic Fe/Gd Multilayers

Spin wave nonreciprocity in domain walls (DWs) allows for unidirectional signal processing in reconfigurable magnonic circuits. Using scanning transmission x-ray microscopy (STXM), we examined coherently-excited magnons propagating in Bloch-like DWs in amorphous Fe/Gd multilayers with perpendicular magnetic anisotropy (PMA). Near 1 GHz we detected magnons with short wavelengths down to $λ= 281$ nm in DWs whose minimum width amounted to $δ_{\rm DW} = 52$ nm. Consistent with micromagnetic simulations, the STXM data reveal their nonreciprocal magnon band structures. We identified Bloch points which disrupted the phase evolution of magnons and induced different $λ$ adjacent to the topological defects. Our observations provide direct evidence of nonreciprocal spin waves within Bloch-like DWs, serving as programmable waveguides in magnonic devices with directed information flow.

cond-mat.mes-hall↗

arXiv2022

Magnetochiral Properties of Spin Waves Existing in Nanotubes with Axial and Circumferential Magnetization

We report experimental studies of spin-wave excitations in individual 22 nm thick Ni80Fe20 nanotubes with diameters of about 150 nm by means of Brillouin light-scattering (BLS) spectroscopy. Irradiated by microwaves we resolve sets of discrete resonances in the center of nanotubes ranging from 2.5 to 12.5 GHz. Comparing to a recent theoretical work and micromagnetic simulations, we identify different characteristic eigenmodes depending on the axial, mixed or vortex configuration. The mixed and vortex states give rise to modes with helical phase profiles substantiating an unusual nature of modes attributed to non-reciprocal spin waves. Our findings provide microscopic insight into tubular spin-wave nanocavities and magnetochiral effects for 3D nanomagnonics.

cond-mat.mes-hall↗

arXiv2021

Confined dipole and exchange spin waves in a bulk chiral magnet with Dzyaloshinskii-Moriya interaction

The Dzyaloshinskii-Moriya interaction (DMI) has an impact on excited spin waves in the chiral magnet Cu$_2$OSeO$_3$ by means of introducing asymmetry on their dispersion relations. The confined eigenmodes of a chiral magnet are hence no longer the conventional standing spin waves. Here we report a combined experimental and micromagnetic modeling study by broadband microwave spectroscopy we observe confined spin waves up to eleventh order in bulk Cu$_2$OSeO$_3$ in the field-polarized state. In micromagnetic simulations we find similarly rich spectra. They indicate the simultaneous excitation of both dipole- and exchange-dominated spin waves with wavelengths down to (47.2 $\pm$ 0.05) nm attributed to the exchange interaction modulation. Our results suggest DMI to be effective to create exchange spin waves in a bulk sample without the challenging nanofabrication and thereby to explore their scattering with noncollinear spin textures.

cond-mat.mtrl-sci↗