Spectroscopy of the spin waves of a synthetic antiferromagnet grown on a piezoelectric substrate

TL;DR

This study explores the microwave magnetic properties of a synthetic antiferromagnet on a piezoelectric substrate, demonstrating its potential for advanced magnon-phonon coupling applications in acousto-magnonics.

Contribution

It provides the first detailed investigation of spin wave dispersion in a CoFeB/Ru/CoFeB synthetic antiferromagnet grown on a piezoelectric substrate, showing comparable properties to traditional substrates.

Findings

Magnetic properties are comparable to those on standard substrates.

The dispersion relation of spin waves aligns with theoretical predictions.

The material platform enables new opportunities in microwave acousto-magnonics.

Abstract

Efficient coupling between magnons and phonons requires material platforms that contain magnetic multilayers with versatile high-frequency properties grown on piezoelectric substrates with large electromechanical coupling coefficients. One of these systems is the CoFeB/Ru/CoFeB Synthetic antiferromagnet grown on Lithium Niobate substrate. We investigate its microwave magnetic properties using a combination of ferromagnetic resonance and propagating spin wave spectroscopy, from which we extract the dispersion relation of the acoustic branch of spin waves. The frequency and the linewidth of this spin wave resonance, its field dependence and its dispersion relation indicate that the magnetic properties are as good as when grown on standard non-piezoelectric substrates, as well as being in line with theory. This new material platform opens opportunities to extend microwave acousto-magnonics beyond the use of single layer magnets.