Electrically Driven Bose-Einstein Condensation of Magnons in Antiferromagnets

TL;DR

This paper proposes a method to achieve Bose-Einstein condensation of magnons in insulating antiferromagnets through electrical means, enabling faster operation at room temperature compared to ferromagnets.

Contribution

It introduces a novel approach for electrically driven magnon condensation in antiferromagnets, highlighting the potential for room-temperature operation and faster dynamics.

Findings

Magnon condensates can be controlled by spin accumulation in adjacent metals.

Condensation can occur for either sign of spin accumulation due to two magnon types.

Operating frequencies are significantly faster than in ferromagnets.

Abstract

We explore routes to realize electrically driven Bose-Einstein condensation of magnons in insulating antiferromagnets. Even in insulating antiferromagnets, the localized spins can strongly couple to itinerant spins in adjacent metals via spin-transfer torque and spin pumping. We describe the formation of steady-state magnon condensates controlled by a spin accumulation polarized along the staggered field in an adjacent normal metal. Two types of magnons exist in antiferromagnets, which carry opposite magnetic moments. Consequently, and in contrast to ferromagnets, Bose-Einstein condensation can occur for either sign of the spin accumulation. This condensation may occur even at room temperature when the interaction with the normal metal is fast compared to the relaxation processes within the antiferromagnet. In antiferromagnets, the operating frequencies of the condensate are orders of magnitude faster than in ferromagnets.