Absence of evidence of spin transport through amorphous Y$_3$Fe$_5$O$_{12}$

TL;DR

This study investigates amorphous YIG films and finds no evidence of spin transport, highlighting the importance of distinguishing charge-related signals from true spin transport in amorphous materials.

Contribution

The paper provides a comprehensive characterization of amorphous YIG films and demonstrates the absence of spin transport signals, emphasizing the need for careful analysis to exclude charge contributions.

Findings

Amorphous YIG is paramagnetic with semiconducting resistivity.

Non-local signals are due to Joule heating, not spin transport.

Careful procedures are necessary to confirm spin transport in amorphous materials.

Abstract

Long-distance transport of spin information in insulators without long-range magnetic order has been recently reported. Here, we perform a complete characterization of amorphous Y$_3$Fe$_5$O$_{12}$ (a-YIG) films grown on top of SiO$_2$. We confirm a clear amorphous structure and paramagnetic behavior of our a-YIG films, with semiconducting behavior resistivity that strongly decays with increasing temperature. The non-local transport measurements show a signal which is not compatible with spin transport and can be attributed to the drop of the a-YIG resistivity caused by Joule heating. Our results emphasize that exploring spin transport in amorphous materials requires careful procedures in order to exclude the charge contribution from the spin transport signals.