Nonstanding spin waves in a single rectangular permalloy microstrip under uniform magnetic excitation

TL;DR

This study directly imaged ferromagnetic resonance modes in a single rectangular permalloy microstrip, revealing nonstanding spin waves under uniform excitation, contrary to typical expectations, with findings supported by micromagnetic simulations.

Contribution

It demonstrates the existence of nonstanding spin waves in a confined microstructure under uniform excitation, challenging the conventional understanding of spin wave behavior.

Findings

Imaged nonstanding spin waves in a microstrip

Confirmed findings with micromagnetic simulations

Observed edge quality effects on spin waves

Abstract

Ferromagnetic resonance modes in a single rectangular Ni$_{80}$Fe$_{20}$ microstrip were directly imaged using time-resolved scanning transmission x-ray microscopy combined with a phase-locked ferromagnetic resonance excitation scheme and the findings were corroborated by micromagnetic simulations. Although under uniform excitation in a single confined microstructure typically standing spin waves are expected, all imaged spin waves showed a nonstanding character both, at and off resonance, the latter being additionally detected with microantenna-based ferromagnetic resonance. The effect of the edge quality on the spin waves was observed in micromagnetic simulations.