Dispersionless propagation of ultra-short spin-wave pulses in ultrathin yttrium iron garnet waveguides

TL;DR

This study demonstrates that in ultrathin yttrium iron garnet waveguides, certain frequencies enable dispersionless propagation of ultra-short spin-wave pulses, facilitated by the interplay of dipolar and exchange interactions, with potential applications in high-speed magnonic systems.

Contribution

It reveals the conditions for dispersionless spin-wave pulse propagation in ultrathin YIG waveguides, combining experimental observations with simulations and analytical models.

Findings

Dispersion broadening is suppressed at specific frequencies.

Dispersionless propagation results from dipolar and exchange interaction balance.

Findings enable high-speed magnonic device development.

Abstract

We study experimentally the propagation of nanosecond spin-wave pulses in microscopic waveguides made of nanometer-thick yttrium iron garnet films. For these studies, we use micro-focus Brillouin light scattering spectroscopy, which provides the possibility to observe propagation of the pulses with high spatial and temporal resolution. We show that, for most spin-wave frequencies, dispersion leads to broadening of the pulse by several times at propagation distances of 10 micrometers. However, for certain frequency interval, the dispersion broadening is suppressed almost completely resulting in a dispersionless pulse propagation. We show that the formation of the dispersion-free region is caused by the competing effects of the dipolar and the exchange interaction, which can be controlled by the variation of the waveguide geometry. These conclusions are supported by micromagnetic simulations and analytical calculations. Our findings provide a simple solution for the implementation of high-speed magnonic systems that require undisturbed propagation of short information-carrying spin-wave pulses.