Spin wave dynamics in artificial anti spin-ice systems: experimental and theoretical investigations

TL;DR

This study explores spin wave behavior in artificial anti spin-ice systems with elliptical antidots, revealing how antidot configuration influences magnonic band gaps and propagation channels, with implications for tunable magnonic devices.

Contribution

It provides experimental and theoretical insights into spin wave spectra in anti-squared spin-ice structures, highlighting the effects of antidot arrangements on magnonic band gaps and propagation channels.

Findings

Flat bands with frequency gaps due to antidot confinement

Propagation channels at 45 degrees lead to band broadening and gap closing

Additional magnonic band gaps depend on antidot configuration

Abstract

Reversed structures of artificial spin-ice systems, where elongated holes with elliptical shape (antidots) are arranged into a square array with two orthogonal sublattices, are referred to as anti-squared spin-ice. Using Brillouin light scattering spectroscopy and plane wave method calculations, we investigate the spin wave propagation perpendicular to the applied field direction for two 20 nm thick Permalloy nanostructures which differ by the presence of single and double elliptical antidots. For the spin waves propagation along the principal antidot lattice axis, the spectrum consists of flat bands separated by several frequency gaps which are the effect of spin wave amplitude confinement in the regions between antidots. Contrarily, for propagation direction at 45 degrees with respect to the antidot symmetry axis, straight and narrow channels of propagation are formed, leading to broadening of bands and closing of the magnonics gaps. Interestingly, in this case, extra magnonic band gaps occur due to the additional periodicity along this direction. The width and the position of these gaps depend on the presence of single or double antidots. In this context, we discuss possibilities for the tuning of spin wave spectra in anti-squared spin ice structures.