Effect of Substrate on Spin-Wave Propagation Properties in Ferrimagnetic Thulium Iron Garnet Thin Films

TL;DR

This study investigates how substrate choice influences spin-wave propagation in thulium iron garnet thin films, revealing substrate-dependent magnetic anisotropy and nonreciprocal spin-wave behavior with potential for magnonic device applications.

Contribution

It provides new insights into substrate effects on spin-wave properties in TmIG films, including anisotropy and nonreciprocity, at room temperature.

Findings

MSSWs propagate up to 80 μm with nonreciprocal behavior on GGG substrates.

Films on sGGG exhibit reciprocal volume spin waves up to 32 μm.

Magnetic anisotropy depends on substrate type, affecting spin-wave propagation.

Abstract

Rare-earth iron garnets have distinctive spin-wave (SW) properties such as low magnetic damping and long SW coherence length making them ideal candidates for magnonics. Among them, thulium iron garnet (TmIG) is a ferrimagnetic insulator with unique magnetic properties including perpendicular magnetic anisotropy (PMA) and topological hall effect at room temperature when grown down to a few nanometers, extending its application to magnon spintronics. Here, the SW propagation properties of TmIG films (thickness of 7-34 nm) grown on GGG and sGGG substrates are studied at room temperature. Magnetic measurements show in-plane magnetic anisotropy for TmIG films grown on GGG and out-of-plane magnetic anisotropy for films grown on sGGG substrates with PMA. SW electrical transmission spectroscopy measurements on TmIG/GGG films unveil magnetostatic surface spin waves (MSSWs) propagating up to 80 um with a SW group velocity of 2-8 km s^-1. Intriguingly, these MSSWs exhibit nonreciprocal propagation, opening new applications in SW functional devices. TmIG films grown on sGGG substrates exhibit forward volume spin waves with a reciprocal propagation behavior up to 32 um.