Perturbation of magnetostatic modes observed by FMRFM

TL;DR

This paper investigates how a magnetic probe affects magnetostatic modes in YIG films using FMRFM, demonstrating local magnetic imaging potential despite long-range interactions.

Contribution

It introduces a theoretical model explaining tip-induced perturbations of magnetostatic modes, enabling local magnetic imaging in ferromagnets.

Findings

Tip magnet induces local potential barriers or wells for magnetostatic waves.

Theoretical model matches experimental perturbations of modes.

Local magnetic imaging is feasible with strong tip fields.

Abstract

Magnetostatic modes of Yttrium Iron Garnet (YIG) films are investigated by ferromagnetic resonance force microscopy (FMRFM). A thin film ``probe'' magnet at the tip of a compliant cantilever introduces a local inhomogeneity in the internal field of the YIG sample. This influences the shape of the sample's magnetostatic modes, thereby measurably perturbing the strength of the force coupled to the cantilever. We present a theoretical model that explains these observations; it shows that tip-induced variation of the internal field creates either a local ``potential barrier'' or ``potential well'' for the magnetostatic waves. The data and model together indicate that local magnetic imaging of ferromagnets is possible, even in the presence of long-range spin coupling, through the induction of localized magnetostatic modes predicted to arise from sufficiently strong tip fields.