Large Nonreciprocity of Shear-Horizontal Surface Acoustic Waves induced by Magnetoelastic Bilayers

TL;DR

This paper demonstrates large nonreciprocity in shear-horizontal surface acoustic waves on a magnetoelastic bilayer, enabling potential nonreciprocal acoustic devices with low wavenumber coupling.

Contribution

It introduces a novel magnetoelastic bilayer system that achieves significant nonreciprocity in SAW transmission, with detailed analysis of the coupling mechanisms and dispersion relations.

Findings

Achieved 30 dB nonreciprocal transmission at 2.33 GHz

Demonstrated phonon-magnon coupling at low wavenumbers

Developed dispersion relation for coupled waves

Abstract

We report large nonreciprocity in the transmission of shear-horizontal surface acoustic waves (SAWs) on LiTaO3 substrate coated with a FeCoSiB/NiFeCu magnetoelastic bilayer. The large difference in saturation magnetization of the two layers not only brings nonreciprocal spin waves (SWs), but also ensures the phonon-magnon (SAWs-SWs) coupling at relatively low wavenumbers. It is found that the angle between the magnetization and the wavevector play important roles in determining the strength of magnetoelastic coupling and nonreciprocity, simultaneously. A large nonreciprocal transmission of SAWs about 30 dB (i.e. 60 dB/mm) is demonstrated at 2.33 GHz. In addition, the dispersion relation between coupled SH-SAWs and nonreciprocal SWs is developed, which provide a good insight into the observed phenomena. Our results offer a convenient approach to implement nonreciprocal SAW isolators or circulators.