Left-handed polarized spin waves in ferromagnets induced by spin-transfer torque

TL;DR

This paper demonstrates that stable left-handed polarized spin waves can be generated in ferromagnets using spin-transfer torque, enabling new ways to encode information in magnonics.

Contribution

It introduces a method to induce and stabilize left-handed polarized spin waves in ferromagnets via spin-polarized currents, which was previously thought impossible.

Findings

Left-handed polarized spin waves can coexist with right-handed ones under certain current conditions.

Micromagnetic simulations confirm the stability of these left-handed spin waves.

The work opens new avenues for studying and utilizing spin wave polarization in magnonics.

Abstract

Polarization is a fundamental property of waves that refers to the orientation of the oscillations. It has been widely used to encode information in photonics and phononics. However, the polarization of spin waves is rarely used yet in magnonics. The reason for this is that only the right-handed polarized spin waves can be accommodated in ferromagnets. Here, we report that stable left-handed polarized spin waves can be introduced into ferromagnets if a spin-polarized electrical current is presented. The right-handed and left-handed polarized spin waves coexist when the current density is larger than a critical value while the system keeps stable. The results are confirmed by micromagnetic simulations. This work provides new playgrounds to study spin waves and points to new findings for future experimental studies.