Journal Article

Spin-wave non-reciprocity in magnetization-graded ferromagnetic films

Gonzalez-Fuentes, C, Landeros, P, Lindner, J, Lenz, K, Alvarado-Seguel, P, Roldán-Molina, A, Schneider, T, Gallardo, R A

2019

Overview

A theoretical approach has been developed to study the spin-wave dynamics of magnetization-graded ferromagnetic films, where the magnetic properties change along the film thickness. The theory is based on a multilayer approach, where the influence of both long-range dipolar interactions and interlayer exchange coupling between sublayers is included. This allows for instance to describe films with a continuous variation of the saturation magnetization along the thickness. A systematic study is carried out in order to analyze different profiles of the saturation magnetization, which is checked through a test of convergence. It is found that the spin-wave dispersion is significantly modified when the strength of the magnetization changes in the bulk film, where a notable frequency non-reciprocity of two counter propagating spin waves is predicted. This is associated with heterosymmetric mode profiles and a modification of the conventional quantization condition associated to perpendicular standing spin-wave modes. Micromagnetic simulations have been carried out to validate the model, where a perfect agreement is reached between both methods. These results show that magnetization-graded ferromagnetic films can be used to channel and control spin waves, thus promoting different kinds of functionalities for magnon-based devices.

• Publisher: IOP Publishing
• Subject: Computer simulation / Ferromagnetic films / Ferromagnetic materials / Film thickness / Interlayers / Magnetic properties / Magnetic saturation / Magnetism / Magnetization / magnetization-graded material / Magnons / Multilayers / non-reciprocity / Physics / Reciprocity / Spin dynamics / spin waves / Wave dispersion / Wave propagation