Magnetic domain walls as broadband spin wave and elastic magnetisation wave emitters

TL;DR

This paper demonstrates that magnetic domain walls in ferromagnetic thin films can serve as tunable, reconfigurable sources of broadband spin waves and elastic waves, with potential applications in wave-based devices.

Contribution

It reveals that magnetic domain walls can directly emit coherent spin and elastic waves, acting as reconfigurable antennas for wave generation and control.

Findings

Domain walls emit directional, low-damped elastic waves tunable by frequency.

Magnetostatic surface spin waves are emitted at higher frequencies, confirmed by simulations.

Wave emission modes are general phenomena relevant for dynamic magnetisation in structured films.

Abstract

We report on the direct observation of spin wave and elastic wave emission from magnetic domain walls in ferromagnetic thin films. Driven by alternating homogeneous magnetic fields the magnetic domain walls act as coherent magnetisation wave sources. Directional and low damped elastic waves below and above the ferromagnetic resonance are excited. The wave vector of the magnetoelastically induced acoustic shear waves is linearly tuned by varying the excitation frequency. Domain wall emitted magnetostatic surface spin waves occur at higher frequencies, which characteristics are confirmed by micromagnetic simulations. The distinct modes of magnetisation wave excitation from micromagnetic objects are a general physical phenomenon relevant for dynamic magnetisation processes in structured magnetic films. Magnetic domain walls can act as reconfigurable antennas for spin wave and elastic wave generation with control of the wave orientation.