All-magnonic Stern-Gerlach effect in antiferromagnets

TL;DR

This paper predicts and demonstrates an all-magnonic Stern-Gerlach effect in antiferromagnets, where spin waves are spatially separated by Dzyaloshinskii-Moriya interactions, advancing antiferromagnetic spintronics.

Contribution

It introduces the concept of an all-magnonic Stern-Gerlach effect in antiferromagnets and demonstrates spin-wave deflection and bi-focusing via DMI interfaces.

Findings

Spin waves are deflected into opposite directions by DMI interfaces.

Bi-focusing of antiferromagnetic spin waves is achieved with curved DMI interfaces.

Thermal magnons with opposite polarizations are spatially separated.

Abstract

The Stern-Gerlach (SG) effect is well known as the spin-dependent splitting of a beam of atoms carrying magnetic moments by a magnetic-field gradient, leading to the concept of electron spin. Antiferromagnets can accommodate two magnon modes with opposite spin polarizations, which is equivalent to the spin property of electrons. Here, we propose the existence of an all-magnonic SG effect in antiferromagnetic magnonic system, where a linearly polarized spin-wave beam is deflected by a straight Dzyaloshinskii-Moriya interaction (DMI) interface into two opposite polarized spin-wave beams propagating in two discrete directions. Moreover, we observe bi-focusing of antiferromagnetic spin waves induced by a curved DMI interface, which can also spatially separate thermal magnons with opposite polarizations. Our findings provide a unique perspective to understand the rich phenomena associated with antiferromagnetic magnon spin and would be helpful for polarization-dependent application of antiferromagnetic spintronic devices.