Spin dynamics in interacting ferromagnetic discs arranged on a Kagome lattice

Artificial spin ice (ASI) consists of periodic arrays of nanomagnets in the shape of elongated elements where competing interactions between the elements lead to geometric frustration. Recently, non-Ising-like ASI have attracted great attention due to their exotic phase diagrams. One example is an array of ferromagnetic nanodiscs.
Here, we report the experimental and theoretical characterization of angular-dependent spin dynamics in arrays of ferromagnetic nanodiscs arranged on a Kagome lattice. The arrangement consists of coupled discs that are 500 nm in diameter. The distance between the Kagome vertices is 76 nm. The magnetic field and microwave frequency dependence obtained by broadband ferromagnetic resonance reveals a rich spectrum of modes that is strongly affected by the microstate of the network. In the high-field range the magnetization is parallel to the applied field, while at low-fields vortices are formed. A comparison of the experimental data with micromagnetic simulations reveals that different subsections of the lattice predominantly contribute to the high-frequency response of the array. Furthermore, we find indications that nucleation and annihilation of vortex-like magnetization configurations in the low-field range affect the dynamics.