Observation and Control of Chiral Spin Frustration in BiYIG Thin Films

TL;DR

This paper demonstrates the control of chiral spin frustration in BiYIG thin films using magnon-driven switching, revealing new possibilities for energy-efficient spintronic devices based on frustrated magnetism.

Contribution

It introduces chiral spin frustration in magnetic thin films and shows how to switch between degenerate states using magnon spin torque with unidirectional control.

Findings

Identified four degenerate frustrated states in BiYIG films.

Achieved controllable, unidirectional switching of spin states via magnons.

Demonstrated potential for energy-efficient spintronic applications.

Abstract

Chiral interactions within magnetic layers stabilize the formation of noncollinear spin textures, which can be leveraged to design devices with tailored magnetization dynamics. Here, we introduce chiral spin frustration in which energetically degenerate magnetic states frustrate the Dzyaloshinskii-Moriya interaction. We demonstrate magnon-driven switching of the chirally frustrated spin states in Bi-substituted yttrium iron garnet thin films. These states are defined by an in-plane macrospin neighboring two out-ofplane spins on either side with opposing chirality. Using scanning nitrogen-vacancy magnetometry and spin pumping, we identified four degenerate frustrated states and achieved their controllable switching via magnon spin torque. Crucially, the switching is unidirectional, with selectivity determined by the incoming magnon direction. This mechanism provides a powerful approach to manipulate frustrated spin states with magnons. Chiral spin frustration unlocks the geometry constraints of conventional frustration, and therefore opens new horizons for frustrated magnetism, paving the way for energy-efficient spintronic devices based on frustratio