Long-Distance Coherent Propagation of High-Velocity Antiferromagnetic Spin Waves
Hanchen Wang, Rundong Yuan, Yongjian Zhou, Yuelin Zhang, Jilei Chen, Song Liu, Hao Jia, Dapeng Yu, Jean‐Philippe Ansermet, Cheng Song, Haiming Yu
Abstract
We report on coherent propagation of antiferromagnetic (AFM) spin waves over a long distance ($\ensuremath{\sim}10\text{ }\text{ }\mathrm{\ensuremath{\mu}}\mathrm{m}$) at room temperature in a canted AFM $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ owing to the Dzyaloshinskii-Moriya interaction (DMI). Unprecedented high group velocities (up to $22.5\text{ }\text{ }\mathrm{km}/\mathrm{s}$) 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 have large wave vectors in the exchange regime and follow a quasilinear dispersion relation. Fitting of experimental data with our theoretical model yields an AFM exchange stiffness length of $1.7\text{ }\text{ }\AA{}$. Our results provide key insights on AFM spin dynamics and demonstrate high-speed functionality for AFM magnonics.