# Spin transport in a magnetic insulator with zero effective damping

## TL;DR

This study demonstrates the control of magnon-mediated spin transport in a thin yttrium iron garnet film through spin-orbit torque, significantly enhancing magnon conductivity and revealing critical damping behavior.

## Contribution

It provides experimental evidence of damping control via spin-orbit torque and observes a large increase in magnon conductivity in a magnetic insulator.

## Key findings

- Magnon conductivity increases by nearly two orders of magnitude above a critical spin-orbit torque.
- Full control of magnetic damping achieved through spin-orbit torque.
- Observation of critical behavior consistent with theoretical predictions of magnon condensates.

## Abstract

Applications based on spin currents strongly profit from the control and reduction of their effective damping and their transport properties. We here experimentally observe magnon mediated transport of spin (angular) momentum through a 13.4 nm thin yttrium iron garnet film with full control of the magnetic damping via spin-orbit torque. Above a critical spin-orbit torque, the fully compensated damping manifests itself as an increase of magnon conductivity by almost two orders of magnitude. We compare our results to theoretical expectations based on recently predicted current induced magnon condensates and discuss other possible origins of the observed critical behaviour.