Imaging non-standing spin-waves in confined micron-sized ferromagnetic structures under uniform excitation

TL;DR

This study combines micromagnetic simulations and time-resolved X-ray microscopy to image and analyze non-standing spin-waves in micron-sized ferromagnetic structures, demonstrating geometry-dependent control of wave modes.

Contribution

It provides direct imaging evidence of non-standing spin-waves in confined structures and shows how sample geometry influences their behavior.

Findings

Confirmed non-standing nature of spin-waves via imaging and simulations.

Demonstrated geometry-dependent modification of spin-wave states.

Validated the use of STXM-FMR for direct spin-wave imaging.

Abstract

A non-standing character of directly imaged spin-waves in confined micron-sized ultrathin permalloy (Ni\textsubscript{80}Fe\textsubscript{20}) structures is reported along with evidence of the possibility to alter the observed state by modifications to the sample geometry. Using micromagnetic simulations the presence of the spin-wave modes excited in the permalloy stripes along with the quasi-uniform modes were calculated. The predicted spin-waves were imaged in direct space using time resolved scanning transmission X-ray microscopy, combined with a ferromagnetic resonance excitation scheme (STXM-FMR). STXM-FMR measurements revealed a non-standing character of the spin-waves. Also it was shown by micromagnetic simulations and confirmed with STXM-FMR results that the observed character of the spin-waves can be influenced by the local magnetic fields in different sample geometries.