# Graded index lenses for spin wave steering

## TL;DR

This paper demonstrates the design and simulation of graded index lenses for steering spin waves in ferromagnetic films, enabling 90 and 180-degree wave deflections and beam division with robustness analysis.

## Contribution

It introduces a novel approach to steer spin waves using graded index lenses created by modulating magnetization or magnetic fields, validated through micromagnetic modelling.

## Key findings

- Lenses can steer spin waves by 90 and 180 degrees.
- The lenses can function as beam dividers.
- The robustness of lenses to profile deviations is analyzed.

## Abstract

We use micromagnetic modelling to demonstrate the operation of graded index lenses designed to steer forward-volume magnetostatic spin waves by 90 and 180 degrees. The graded index profiles require the refractive index to diverge in the lens center, which, for spin waves, can be achieved by modulating the saturation magnetization or external magnetic field in a ferromagnetic film by a small amount. We also show how the 90$^\circ$ lens may be used as a beam divider. Finally, we analyse the robustness of the lenses to deviations from their ideal profiles.