Apparent Zero-Momentum Signals from Magnon--Magnon Interference in Near-Field Spin-Wave Imaging
Abstract
Spatially resolved measurements of coherent waves are commonly read as direct maps of the underlying eigenmode spectrum. We show that this interpretation fails in near-field imaging of multimode spin-wave transport. Scanning nitrogen-vacancy magnetometry of yttrium iron garnet reveals pronounced apparent low-wave-vector signals at frequencies for which no propagating spin-wave mode exists. By tuning the probe-sample distance and modeling the anisotropic near-field response, we identify their origin as coherent mixing between directly excited Damon-Eshbach waves and defect- or transducer-scattered spin waves: the measured signal acquires spatial Fourier components at the difference wave vector kexc−kscat, which can vanish even though both constituent waves carry finite momentum. These results establish that near-field spectra of coherent excitations are interferometric field spectra rather than eigenmode maps, providing both a caution and a framework for identifying scattering processes in nanoscale magnonic devices.
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BibTeX
@misc{berthomier2026apparent,
title = {{Apparent Zero-Momentum Signals from Magnon--Magnon Interference in Near-Field Spin-Wave Imaging}},
author = {Julien Berthomier and Romain Lebrun and Vincent Cros and Jamal Ben Youssef and Karim Bouzehouane and Abdelmadjid Anane},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09922},
eprint = {2609.09922},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.09922},
}
RIS
TY - UNPB
TI - Apparent Zero-Momentum Signals from Magnon--Magnon Interference in Near-Field Spin-Wave Imaging
AU - Julien Berthomier
AU - Romain Lebrun
AU - Vincent Cros
AU - Jamal Ben Youssef
AU - Karim Bouzehouane
AU - Abdelmadjid Anane
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2609.09922
UR - https://arxiv.org/abs/2609.09922
AB - Spatially resolved measurements of coherent waves are commonly read as direct maps of the underlying eigenmode spectrum. We show that this interpretation fails in near-field imaging of multimode spin-wave transport. Scanning nitrogen-vacancy magnetometry of yttrium iron garnet reveals pronounced apparent low-wave-vector signals at frequencies for which no propagating spin-wave mode exists. By tuning the probe-sample distance and modeling the anisotropic near-field response, we identify their origin as coherent mixing between directly excited Damon-Eshbach waves and defect- or transducer-scattered spin waves: the measured signal acquires spatial Fourier components at the difference wave vector k_exc−k_scat, which can vanish even though both constituent waves carry finite momentum. These results establish that near-field spectra of coherent excitations are interferometric field spectra rather than eigenmode maps, providing both a caution and a framework for identifying scattering processes in nanoscale magnonic devices.
ER -