# Frustration and thermalisation in an artificial magnetic quasicrystal

## TL;DR

This study explores artificial magnetic quasicrystals based on Penrose tilings, revealing frustration, emergent ground states, and the effects of thermal treatment on magnetic domain structures.

## Contribution

It introduces a novel class of magnetic quasicrystals with topologically induced frustration and characterizes their magnetic configurations and domain behaviors.

## Key findings

- Identification of a ground state with a quasi-one-dimensional skeleton and flippable clusters.
- Superdomain sizes increase with stronger coupling and thermal treatments.
- Emergent frustration prevents construction of ground states from individual vertex ground states.

## Abstract

We have created and studied artificial magnetic quasicrystals based on Penrose tiling patterns of interacting nanomagnets that lack the translational symmetry of spatially periodic artificial spin ices. Vertex-level degeneracy and frustration induced by the network topology of the Penrose pattern leads to a low energy configuration that we propose as a ground state. Topologically induced emergent frustration means that this ground state cannot be constructed from vertices in their ground states. It has two parts, a quasi-one-dimensional rigid "skeleton" that spans the entire pattern and is capable of long-range order, and "flippable" clusters of macrospins within it. These lead to macroscopic degeneracy for the array as a whole. Magnetic force microscopy imaging of Penrose tiling arrays revealed superdomains that are larger for more strongly coupled arrays. The superdomain size is larger after AC-demagnetisation and especially after annealing the array above its blocking temperature.