Long-distance spin-transport across the Morin phase transition up to room temperature in ultra-low damping single crystals of the antiferromagnet {\alpha}-Fe2O3

TL;DR

This study demonstrates long-distance spin-transport at room temperature in an antiferromagnetic material with easy-plane anisotropy, showing potential for magnon-based devices due to low magnetic damping and persistent spin signals.

Contribution

It reveals that linearly polarized magnons can carry spin over micrometer distances in hematite across the Morin transition, expanding the understanding of spin-transport in antiferromagnets.

Findings

Spin-transport persists through the Morin transition.

Dephasing lengths of spin waves are in the micrometer range.

Magnetic damping is below 0.0001, enabling long-distance transport.

Abstract

Antiferromagnetic materials can host spin-waves with polarizations ranging from circular to linear depending on their magnetic anisotropies. Until now, only easy-axis anisotropy antiferromagnets with circularly polarized spin-waves were reported to carry spin-information over long distances of micrometers. In this article, we report long-distance spin-transport in the easy-plane canted antiferromagnetic phase of hematite and at room temperature, where the linearly polarized magnons are not intuitively expected to carry spin. We demonstrate that the spin-transport signal decreases continuously through the easy-axis to easy-plane Morin transition, and persists in the easy-plane phase through current induced pairs of linearly polarized magnons with dephasing lengths in the micrometer range. We explain the long transport distance as a result of the low magnetic damping, which we measure to be below 0.0001 as in the best ferromagnets. All of this together demonstrates that long-distance transport can be achieved across a range of anisotropies and temperatures, up to room temperature, highlighting the promising potential of this insulating antiferromagnet for magnon-based devices.