Study of the magnetoelastic effect in nickel and cobalt thin films at GHz range using X-ray microscopy

TL;DR

This study investigates magnetoelastic effects in nickel and cobalt thin films at GHz frequencies using X-ray microscopy, revealing wave propagation, amplitude quantification, and a potential speed limit for magnetoelastic coupling.

Contribution

It introduces direct imaging and quantification of magnetoacoustic waves in ferromagnetic films at GHz frequencies, combining experimental and simulation approaches.

Findings

Visualization of magnetoacoustic wave amplitudes

Propagation over millimeter distances

Detection of a speed limit at 3 GHz

Abstract

We use surface acoustic waves of 1 and 3 GHz in hybrid piezoelectric-magnetic systems with either cobalt or nickel as a magnetic layer to generate magnetoacoustic waves and directly image them using stroboscopic X-ray magnetic circular dichroism imaging. Our measurements visualize and quantify the amplitudes of both acoustic and magnetic components of the magnetoacoustic waves, which are generated in the ferromagnetic layer and can propagate over millimeter distances. Additionally, we quantifiedy the magnetoelastic strain component for cobalt and nickel through micromagnetic simulations. We obtained a drop in the magnetoacoustic signal at 3 GHz suggesting a speed limit for the efficient magnetoelastic coupling in our hybrid devices.