Long-distance propagation of high-velocity antiferromagnetic spin waves

TL;DR

This paper demonstrates long-distance, high-velocity antiferromagnetic spin wave propagation at room temperature in $ ext{Fe}_2 ext{O}_3$, with experimental and theoretical analysis revealing potential for high-speed AFM magnonic devices.

Contribution

It provides the first experimental observation of long-distance, high-velocity AFM spin waves in $ ext{Fe}_2 ext{O}_3$ at room temperature, supported by a detailed analytical dispersion model.

Findings

Spin waves propagate over ~10 μm at room temperature.

Group velocities reach up to 22.5 km/s.

Dispersion relation fits yield an exchange stiffness length of 1.7 Å.

Abstract

We report on coherent propagation of antiferromagnetic (AFM) spin waves over a long distance ($\sim$10 $\mu$m) at room temperature in a canted AFM $\alpha$-Fe$_2$O$_3$ with the Dzyaloshinskii-Moriya interaction (DMI). Unprecedented high group velocities (up to 22.5 km/s) are characterized by microwave transmission using all-electrical spin wave spectroscopy. We derive analytically AFM spin-wave dispersion in the presence of the DMI which accounts for our experimental results. The AFM spin waves excited by nanometric coplanar waveguides with large wavevectors enter the exchange regime and follow a quasi-linear dispersion relation. Fitting of experimental data with our theoretical model yields an AFM exchange stiffness length of 1.7 angstrom. Our results provide key insights on AFM spin dynamics and demonstrate high-speed functionality for AFM magnonics.