Ultrastrong magnon-magnon coupling and chiral spin-texture control in a dipolar 3D multilayered artificial spin-vortex ice

TL;DR

This paper presents a 3D multilayered artificial spin ice system demonstrating ultrastrong magnon-magnon coupling, chiral spin-texture control, and reconfigurable magnonic states driven by inter-layer dipolar interactions.

Contribution

It introduces a novel 3D magnonic metamaterial with multilayered nanoarrays enabling ultrastrong coupling and programmable chiral spin textures, expanding control over 3D magnetic microstates.

Findings

Achieved normalized magnon-magnon coupling rate of 0.57.

Demonstrated GHz mode shifts in zero field.

Controlled magnonic spectra via chiral microstate programming.

Abstract

Strongly-interacting nanomagnetic arrays are ideal systems for exploring reconfigurable magnonics. They provide huge microstate spaces and integrated solutions for storage and neuromorphic computing alongside GHz functionality. These systems may be broadly assessed by their range of reliably accessible states and the strength of magnon coupling phenomena and nonlinearities. Increasingly, nanomagnetic systems are expanding into three-dimensional architectures. This has enhanced the range of available magnetic microstates and functional behaviours, but engineering control over 3D states and dynamics remains challenging. Here, we introduce a 3D magnonic metamaterial composed from multilayered artificial spin ice nanoarrays. Comprising two magnetic layers separated by a non-magnetic spacer, each nanoisland may assume four macrospin or vortex states per magnetic layer. This creates a system with a rich $16^N$ microstate space and intense static and dynamic dipolar magnetic coupling. The system exhibits a broad range of emergent phenomena driven by the strong inter-layer dipolar interaction, including ultrastrong magnon-magnon coupling with normalised coupling rates of $\frac{\Delta \omega}{\gamma} = 0.57$, GHz mode shifts in zero applied field and chirality-selective magneto-toroidal microstate programming and corresponding magnonic spectral control.