# Long-distance spin transport in a disordered magnetic insulator

## TL;DR

This study demonstrates efficient long-distance spin transport in amorphous magnetic insulators, revealing that disorder does not hinder, and may even enhance, spin signal propagation, opening new avenues for spintronic applications.

## Contribution

It provides the first experimental evidence of significant spin transport in disordered magnetic insulators, challenging the notion that long-range order is necessary for effective spin conduction.

## Key findings

- Large non-local spin signals observed over 100 microns.
- Spin transport signals are orders of magnitude larger than in crystalline counterparts.
- Thermal gradients strongly influence spin transport in disordered systems.

## Abstract

Spin transport through magnetic insulators via magnons has recently been explored for a growing variety of magnetic systems with long-range order and well-understood spin excitation spectra. Here we show dramatic effects of spin transport through an amorphous magnetic insulator, which is both magnetically and structurally disordered. We generate and detect spin flow though amorphous yttrium-iron-garnet ($a$-YIG) thin films in a non-local geometry by use of the spin Hall and inverse spin Hall effects in platinum strips separated by 10 or more microns. By comparing non-local spin transport in $a$-YIG on suspended micromachined thermal isolation platforms to the same experiment performed on a bulk substrate, we show strong effects of in-plane thermal gradients on spin transport in the disordered magnetic insulator. The resulting non-local voltage signals are orders of magnitude larger than those seen in crystalline magnetic insulators, with easily measurable spin signals seen even at distances in excess of $100$ microns. In analogy to heat transport, where disordered materials support a range of vibrational excitations that can allow large thermal conductivities, we suggest that efficient spin transport in disordered magnetic systems can occur via a similar spectrum of excitations that relies on strong local exchange interactions and does not require long-range order. This work not only opens a new area for fundamental experimental and theoretical studies of spin transport, but also sets a new direction in materials science for magnonic and spintronic devices.