Nonreciprocal spin-wave dispersion in magnetic bilayers

TL;DR

This paper investigates how the nonreciprocal propagation of spin waves in bilayer ferromagnetic systems can be controlled by material parameters, with potential applications in magnonic devices and circuits.

Contribution

It provides a detailed numerical and experimental analysis of nonreciprocal spin-wave dispersion in heterostructures, highlighting how material properties influence nonreciprocity.

Findings

Nonreciprocity can reach several GHz under optimized conditions.

Material parameter tuning enables precise control of nonreciprocal behavior.

Experimental results confirm numerical predictions.

Abstract

Nonreciprocal spin-wave propagation in bilayer ferromagnetic systems has attracted significant attention due to its potential to precisely quantify material parameters as well as for applications in magnonic logic and information processing. In this study we investigate the nonreciprocity of spin-wave dispersions in heterostructures consisting of two distinct ferromagnetic materials, focusing on the influence of saturation magnetization and thickness of the magnetic layers. We exploit Brillouin light scattering to confirm numerical calculations which are conducted with the finite element software TETRAX. An extensive numerical analysis reveals that the nonreciprocal behavior is strongly influenced by the changing material parameters, with asymmetry in the spin-wave propagation direction reaching several GHz under optimized conditions. Our findings demonstrate that tailoring the bilayer composition enables precise control over nonreciprocity, providing a pathway for engineering efficient unidirectional spin-wave devices. These results offer a deeper understanding of hybrid ferromagnetic systems and open avenues for designing advanced magnonic circuits.