Coherent Spin Waves in Curved Ferromagnetic Nanocaps of a 3D‐Printed Magnonic Crystal

Why It Matters

Robust edge‑dominated magnons in a 3D architecture enable ultrafast, low‑energy microwave processing and topologically protected data transport.

Key Takeaways

• 3D woodpile fabricated via two‑photon lithography
• 30‑nm nickel coating enables ferromagnetic resonance
• Edge modes localized in curved nanocaps remain robust
• Phase evolution observed along crystal edges
• Potential for ultrafast, edge‑dominated magnonic circuits

Pulse Analysis

Magnonics, the study of spin‑wave quanta called magnons, promises to complement or replace charge‑based electronics for high‑speed, low‑power signal processing. While planar magnonic devices have matured, extending these concepts into the third dimension has remained largely theoretical due to fabrication challenges. A truly three‑dimensional magnonic crystal can host richer band structures, including minibands and topologically protected edge states, which are essential for robust, non‑reciprocal microwave components.

The breakthrough reported leverages two‑photon polymerization to print a woodpile lattice, followed by atomic‑layer deposition of a 30‑nm nickel film that imparts ferromagnetic functionality. Integrated with an on‑chip microresonator, the structure exhibits coherent spin‑wave resonances at 14 GHz and 24 GHz, directly mapping the face‑centered cubic symmetry of the lattice. Micromagnetic simulations confirm that the most striking modes are confined to the curved nanocaps at the crystal edges, maintaining their intensity across a wide range of magnetic‑field orientations and displaying an unexpected phase progression along the edge—a hallmark of emerging topological behavior.

These findings signal a pivotal step toward practical 3D magnonic circuitry. Edge‑localized magnons that are resilient to disorder could serve as information carriers in future microwave‑frequency interconnects, enabling ultrafast data routing with minimal energy loss. Moreover, the scalable nanoprinting approach aligns with existing semiconductor manufacturing pipelines, suggesting that commercial adoption of 3D magnonic components for next‑generation communication and computing systems is within reach. Continued exploration of topological magnon bands may unlock new paradigms for secure, high‑bandwidth signal processing.