# Influence of nonmagnetic dielectric spacers on the spin wave response of one-dimensional planar magnonic crystals

## TL;DR

This study investigates how non-magnetic spacers affect the spin wave spectra in one-dimensional magnonic crystals, revealing that spacers significantly influence resonance frequencies and wave velocities through dipolar interactions.

## Contribution

The paper provides detailed numerical analysis of how non-magnetic spacers modify spin wave spectra in 1D magnonic crystals, highlighting the roles of dipolar interactions and geometric parameters.

## Key findings

- Non-magnetic spacers significantly shift ferromagnetic resonance frequencies.
- Spacers reduce spin wave group velocity and flatten magnonic bands.
- Dipolar interactions and shape anisotropy are key factors influenced by spacers.

## Abstract

The one-dimensional planar magnonic crystals are usually fabricated as a sequence of stripes intentionally or accidentally separated by non-magnetic spacers. The influence of spacers on shaping the spin wave spectra is complex and still not completely clarified. We performed the detailed numerical studies of the one-dimensional single- and bi-component magnonic crystals comprised of a periodic array of thin ferromagnetic stripes separated by non-magnetic spacers. We showed that the dynamic dipolar interactions between the stripes mediated by non-magnetic spacer, even ultra-narrow, significantly shift up the frequency of the ferromagnetic resonance and simultaneously reduce the spin wave group velocity, which is manifested by the flattening of the magnonic band. We attributed these changes in the spectra to the modifications of dipolar pinning and shape anisotropy both dependent on the width of the spacers and the thickness of the stripes, as well as to the dynamical magnetic volume charges formed due to inhomogeneous spin wave amplitude.