Nearly Isotropic Magnon Transport in Epitaxial Lithium Aluminum Ferrite Thin Films

TL;DR

This study demonstrates nearly isotropic magnon transport in epitaxial lithium aluminum ferrite thin films, highlighting their potential for low-loss, isotropic spin-based information transport.

Contribution

We experimentally show that epitaxial lithium aluminum ferrite thin films exhibit nearly identical magnon diffusion lengths along different in-plane directions, indicating isotropic magnon transport.

Findings

Magnon diffusion lengths are nearly identical along [100] and [110] directions at 250 K.

The isotropy is consistent with a nearly isotropic exchange stiffness.

Results support spinel ferrites as platforms for isotropic magnon transport.

Abstract

Low-loss magnetic insulating thin films are promising for information transport via magnons, where isotropic in-plane magnon propagation is desirable. We report nonlocal measurements of electrically and thermally generated magnons in epitaxial (001) lithium aluminum ferrite Li$_{0.5}$Al$_{0.7}$Fe$_{1.8}$O$_4$ thin films with pronounced fourfold in-plane magnetic anisotropy. By measuring the inverse spin Hall signal as a function of the magnon diffusion distance, we deduce magnon diffusion lengths that are nearly identical along the [100] and [110] directions at 250~K. This isotropy is consistent with a nearly isotropic exchange stiffness. These results highlight spinel ferrites as viable platforms for isotropic magnon transport.