Magnon drag in a metal-insulating antiferromagnet bilayer

TL;DR

This paper investigates how an electron current in a metal-antiferromagnet bilayer can induce and enhance magnon spin-currents through interfacial exchange coupling, with potential control via temperature and magnon mode splitting.

Contribution

It introduces a mechanism for generating and controlling magnon spin-currents in antiferromagnetic insulators using interfacial exchange coupling with a normal metal.

Findings

Magnon spin-current can be generated via electron current in the metal.

Asymmetry at the interface enables magnon spin-current generation.

Increasing temperature or spin-splitting enhances magnon current.

Abstract

We study a bilayer structure consisting of an antiferromagnetic insulator and a normal metal. An electron current is driven in the normal metal with direction parallel to the interface between the materials. Due to interfacial exchange coupling between the localized spins in the antiferromagnet and the itinerant electrons in the normal metal, a magnon current can then be induced in the antiferromagnet. Using an uncompensated antiferromagnetic interface, creating an asymmetry in the interfacial coupling to the two degenerate magnon modes, we find that it is possible to generate a magnon spin-current. The magnon spin-current can be enhanced by increasing the temperature or by spin-splitting the magnon modes.