FMR Modes in Connected Kagome Artificial Spin Ice*

Artificial spin ices (ASI) are typically periodic, 2-D lattices of sub-micron, ferromagnetic thin-film segments [1]. Each segment is elongated to attain a strong shape-anisotropy that induces single-domain, Ising-like spins. ASI lattices designed to exhibit frustration of the Ising dipole interactions (e.g., Kagome arrays). ASI exhibit complex dynamics that vary with lattice type and applied DC field orientation. We use broad-band ferromagnetic resonance (FMR) and micromagentic simulations to characterize FMR modes in connected, Kagome ASI that is complicated by additional short-range exchange interactions and domain walls within lattice vertices. We use a field protocol to set an ASI in a particular magnetization state. Generally, the highest-frequency FMR mode in ASI arises in segments whose Ising moment makes the smallest angle with the applied field [1]. In contrast, we show that control of the magnetization state of the vertices determine which segments resonate at the highest frequency. Our findings improve understanding of FMR modes in ASI and provide new guidelines for controlling resonance modes in magnonic devices.
[1] Skjærvø, S. H., et al. "Advances in artificial spin ice." Nature Reviews Physics (2019): 1-16.