Magnetoelastic effect through coupled surface acoustic waves and spin waves in ferromagnetic Cobalt thin films

Abstract

Magnetostriction is the property of a material to modify its shape upon a change of its magnetization. Converserly, the magnetoelastic effect accounts for the changes in magnetization after a material’s deformation. Surface acoustic waves (SAW) are sound waves that travel parallel to the surface of an elastic material, thus creating a dynamic strain. It is known that SAW induced in a piezoelectric substrate can couple to a ferromagnetic material creating spin waves (SW), but has not yet been widely characterized in many materials. In this paper we want to observe the dynamic magnetoelastic effect in a Cobalt (Co) thin film deposited on a piezoelectric substrate capable to produce SAW. Transmission of SAW will be studied as a function of the magnetic field and the relative angle between field and SAW propagation. We observe absorption of SAW depending on the magnetic state of the Co thin film. This paper will furthermore be complemented with direct observation of SAW and SW through X-ray magnetic circular dichroism imaging. Thus the effects observed in the transmission of SAW can directly be correlated to SW and magnetic switching in the material