Strongly-interacting nanomagnetic arrays are ideal systems for exploring
reconfigurable magnonics. They provide huge microstate spaces and inte grated 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 non linearities. 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 meta material composed from multilayered artificial spin ice nanoarrays. Compris ing 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 16N microstate space and intense static and dynamic dipolar
magnetic coupling. The system exhibits a broad range of emergent phenom ena driven by the strong inter-layer dipolar interaction, including ultrastrong
magnon-magnon coupling with normalised coupling rates of Δf
ν = 0:57, GHz
mode shifts in zero applied field and chirality-control of magnetic vortex
microstates with corresponding magnonic spectra.