Direct Imaging of Complex Spin Ice Behavior and Ordered Sublattices in Artificial Ferromagnetic Quasicrystals

Abstract

We have imaged magnetization textures of permalloy films patterned into Penrose P2 tilings (P2T) using scanning electron microscopy with polarization analysis (SEMPA). P2T film segments have near-uniform, bipolar magnetization, similar to artificial spin ices, but with asymmetric vertex coordination that induces a more complex spin ice behavior mediated by exchange interactions in vertex domain walls. Numerical simulations including long-range dipole interactions agree with SEMPA images of as-grown P2T, and predict a ferromagnetic ground state for a 2D P2T lattice of classical Ising spins.