Defect-sensitive high-frequency modes in a three-dimensional artificial magnetic crystal

Modern three-dimensional nanofabrication methods make it possible to generate arbitrarily shaped nanomagnets, including periodic networks of interconnected magnetic nanowires. Structurally similar to optical or acoustic metamaterials, these arrays could represent magnetic variants of such artificial materials. Using micromagnetic simulations, we investigate a three-dimensional array of interconnected magnetic nanowires with intersection points corresponding to atomic positions of a diamond lattice. The high-frequency excitation spectrum of this artificial magnetic crystal (AMC) is shaped by both microstructure and magnetization configuration. The system displays characteristics of three-dimensional artificial spin ice and can host Dirac-type magnetic defect structures, which are associated with characteristic magnonic frequencies. We demonstrate how magnetic configurations and structural defects affect the spectrum and show that external magnetic fields allow continuous tuning of the overall frequency response. While our study focuses on fundamental aspects, the findings suggest AMCs may serve as reconfigurable magnonic media for future magnonic or neuromorphic devices.