Magnon-mediated interlayer coupling in an all-antiferromagnetic junction

TL;DR

This paper demonstrates room-temperature magnon-mediated interlayer coupling in an all-antiferromagnetic junction, revealing a novel bosonic excitation-based interaction that could advance antiferromagnetic spintronics and magnonics.

Contribution

It reports the first observation of static interlayer coupling mediated by magnons in an antiferromagnetic junction at room temperature, showcasing a new bosonic quasi-particle interaction.

Findings

Strong orthogonal coupling of Nél vectors in Fe2O3 layers

Magnon excitation in Cr2O3 mediates the coupling

Potential for ultrahigh-density antiferromagnetic spintronics

Abstract

The interlayer coupling mediated by fermions in ferromagnets brings about parallel and anti-parallel magnetization orientations of two magnetic layers, resulting in the giant magnetoresistance, which forms the foundation in spintronics and accelerates the development of information technology. However, the interlayer coupling mediated by another kind of quasi-particle, boson, is still lacking. Here we demonstrate such a static interlayer coupling at room temperature in an antiferromagnetic junction Fe2O3/Cr2O3/Fe2O3, where the two antiferromagnetic Fe2O3 layers are functional materials and the antiferromagnetic Cr2O3 layer serves as a spacer. The N\'eel vectors in the top and bottom Fe2O3 are strongly orthogonally coupled, which is bridged by a typical bosonic excitation (magnon) in the Cr2O3 spacer. Such an orthogonally coupling exceeds the category of traditional collinear interlayer coupling via fermions in ground state, reflecting the fluctuating nature of the magnons, as supported by our magnon quantum well model. Besides the fundamental significance on the quasi-particle-mediated interaction, the strong coupling in an antiferromagnetic magnon junction makes it a realistic candidate for practical antiferromagnetic spintronics and magnonics with ultrahigh-density integration.