Resonant scattering of spin waves from a region of inhomogeneous magnetic field in a ferromagnetic film

TL;DR

This paper investigates how localized magnetic field inhomogeneities, induced by a current, affect the transmission and phase of spin waves in a ferromagnetic film, revealing non-monotonic transmission behavior due to scattering resonances.

Contribution

It provides both experimental and theoretical analysis of spin wave scattering by magnetic field inhomogeneities, identifying a resonance effect that influences transmission.

Findings

Transmission amplitude shows non-monotonic dependence on current.

Presence of a scattering resonance causes a maximum in transmission.

Current direction determines whether the inhomogeneity acts as a barrier or well.

Abstract

The transmission of a dipole-dominated spin wave in a ferromagnetic film through a localised inhomogeneity in the form of a magnetic field produced by a dc current through a wire placed on the film surface was studied experimentally and theoretically. It was shown that the amplitude and phase of the transmitted wave can be simultaneously affected by the current induced field, a feature that will be relevant for logic based on spin wave transport. The direction of the current creates either a barrier or well for spin wave transmission. The main observation is that the current dependence of the amplitude of the spin wave transmitted through the well inhomogeneity is non-monotonic. The dependence has a minimum and an additional maximum. A theory was constructed to clarify the nature of the maximum. It shows that the transmission of spin waves through the inhomogeneity can be considered as a scattering process and that the additional maximum is a scattering resonance.