Spin waves in micro-structured yttrium iron garnet nanometer-thick films

TL;DR

This study explores spin-wave propagation in a 40 nm thick yttrium iron garnet waveguide, revealing decay characteristics and damping constants, and compares experimental observations with theoretical mode interference calculations.

Contribution

It provides the first detailed experimental analysis of spin waves in micro-structured yttrium iron garnet nanometer-thick films, including damping measurements and mode interference comparison.

Findings

Spin-wave amplitude decays exponentially over approximately 10 micrometers.

The measured Gilbert damping constant is higher than in unstructured films.

Experimental spin-wave patterns agree with theoretical mode interference calculations.

Abstract

We investigated the spin-wave propagation in a micro-structured yttrium iron garnet waveguide of $40$ nm thickness. Utilizing spatially-resolved Brillouin light scattering microscopy, an exponential decay of the spin-wave amplitude of $(10.06 \pm 0.83)$ $\mu$m was observed. This leads to an estimated Gilbert damping constant of $\alpha=(8.79\pm 0.73)\times 10^{-4}$, which is larger than damping values obtained through ferromagnetic resonance measurements in unstructured films. The theoretically calculated spatial interference of waveguide modes was compared to the spin-wave pattern observed experimentally by means of Brillouin light scattering spectroscopy.