Nonreciprocal propagation of surface acoustic wave in Ni/LiNbO3

TL;DR

This study demonstrates nonreciprocal surface acoustic wave propagation in Ni/LiNbO3 devices, driven by magnetoelastic coupling and symmetry breaking, with controllability via magnetic field orientation.

Contribution

It reveals the shape-dependent nonreciprocal propagation of surface acoustic waves in Ni/LiNbO3, highlighting the role of magnetoelastic coupling and symmetry considerations.

Findings

Nonreciprocal propagation depends on wave vector sign.

Reversible by 180° magnetic field rotation.

Shape of Ni film influences nonreciprocity.

Abstract

We have investigated surface acoustic wave propagation in Ni/LiNbO$_3$ hybrid devices. We have found the absorption and phase velocity are dependent on the sign of wave vector in a device, which indicates the nonreciprocal propagation characteristic of systems with time reversal and spatial inversion simultaneously broken symmetries. The nonreciprocity is reversed by the 180$^\circ$ rotation of magnetic field. Nonreciprocity seems largely dependent on the shape of ferromagnetic Ni film. The origin of these observations is ascribed to film shape dependent magnetoelastic coupling.