Experimental and Numerical Understanding of Localized Spin Wave Mode Behavior in Broadly Tunable Spatially Complex Magnetic Configurations

TL;DR

This study combines experimental FMRFM measurements and micromagnetic simulations to analyze and control localized spin wave modes in ferromagnetic films, enabling high-resolution magnetic imaging and advancing understanding of nanoscale spin dynamics.

Contribution

It provides a detailed analysis of localized spin wave modes in complex magnetic configurations and demonstrates broad tunability and accurate modeling, enhancing FMRFM's application scope.

Findings

Localized modes can be tuned by magnetic field orientation.

Micromagnetic simulations match experimental spectra accurately.

Tightly confined spin wave modes enable high spatial resolution imaging.

Abstract

Spin wave modes confined in a ferromagnetic film by the spatially inhomogeneous magnetic field generated by a scanned micromagnetic tip of a ferromagnetic resonance force microscope (FMRFM) enable microscopic imaging of the internal fields and spin dynamics in nanoscale magnetic devices. Here we report a detailed study of spin wave modes in a thin ferromagnetic film localized by magnetic field configurations frequently encountered in FMRFM experiments, including geometries in which the probe magnetic moment is both parallel and antiparallel to the applied uniform magnetic field. We demonstrate that characteristics of the localized modes, such as resonance field and confinement radius, can be broadly tuned by controlling the orientation of the applied field relative to the film plane. Micromagnetic simulations accurately reproduce our FMRFM spectra allowing quantitative understanding of the localized modes. Our results reveal a general method of generating tightly confined spin wave modes in various geometries with excellent spatial resolution that significantly facilitates the broad application of FMRFM. This paves the way to imaging of magnetic properties and spin wave dynamics in a variety of contexts for uncovering new physics of nanoscale spin excitations.