# Excitation of unidirectional exchange spin waves by a nanoscale magnetic grating

## TL;DR

This paper demonstrates the experimental excitation of nearly perfectly unidirectional exchange spin waves using a nanoscale magnetic grating, advancing magnonic logic device development by controlling spin wave propagation direction.

## Contribution

It introduces a novel method to achieve unidirectional spin wave excitation via a nanoscale magnetic grating, leveraging magneto-dipolar interactions for potential magnonic logic applications.

## Key findings

- Achieved nearly perfect unidirectional excitation of exchange spin waves.
- Reversal of magnetic configurations switches the spin wave propagation direction.
- Model explains the unidirectional excitation through magneto-dipolar interaction chirality.

## Abstract

Magnon spintronics is a prosperous field that promises beyond-CMOS technology based on elementary excitations of the magnetic order that act as information carriers for future computational architectures. Unidirectional propagation of spin waves is key to the realization of magnonic logic devices. However, previous efforts to enhance the Damon-Eshbach-type nonreciprocity did not realize (let alone control) purely unidirectional propagation. Here we experimentally demonstrate excitations of unidirectional exchange spin waves by a nanoscale magnetic grating consisting of Co nanowires fabricated on an ultrathin yttrium iron garnet film. We explain and model the nearly perfect unidirectional excitation by the chirality of the magneto-dipolar interactions between the Kittel mode of the nanowires and the exchange spin waves of the film. Reversal of the magnetic configurations of film and nanowire array from parallel to antiparallel changes the direction of the excited spin waves. Our results raise the prospect of a chiral magnonic logic without the need for fragile surface states.

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Source: https://tomesphere.com/paper/1903.00638