Magnon Transport in the Presence of Antisymmetric Exchange in a Weak Antiferromagnet

TL;DR

This paper investigates how the Dzyaloshinskii-Moriya interaction influences magnon transport in antiferromagnetic hematite, revealing reconfigurability and hysteresis effects under different magnetic field orientations.

Contribution

It provides the first quantitative measurement of DMI strength in hematite and demonstrates its role in controlling magnon transport reconfigurability.

Findings

DMI creates an effective field measurable by magnetometry and transport.

Reconfigurability of magnon transport depends on magnetic field orientation.

Hysteresis in magnon transport is observed around the easy-axis, influenced by DMI and Zeeman energy.

Abstract

The Dzyaloshinskii-Moriya interaction (DMI) is at the heart of many modern developments in the research field of spintronics. DMI is known to generate noncollinear magnetic textures, and can take two forms in antiferromagnets: homogeneous or inter-sublattice, leading to small, canted moments and inhomogeneous or intra-sublattice, leading to formation of chiral structures. In this work, we first determine the strength of the effective field created by the DMI, using SQUID based magnetometry and transport measurements, in thin films of the antiferromagnetic iron oxide hematite, $\alpha$-Fe$_2$O$_3$. We demonstrate that DMI additionally introduces reconfigurability in the long distance magnon transport in these films under different orientations of a magnetic field. This arises as a hysteresis centred around the easy-axis direction for an external field rotated in opposing directions whose width decreases with increasing magnetic field as the Zeeman energy competes with the effective field created by the DMI.