Understanding Thermal Annealing of Artificial Spin Ice

TL;DR

This study investigates how thermal annealing influences the magnetic configurations in artificial spin ice, revealing the effects of physical parameters and thermal processes on system equilibration and low-energy state attainment.

Contribution

It provides new insights into the thermalization mechanisms in artificial spin ice by examining the effects of island thickness, shape, and temperature on magnetic ordering.

Findings

Thicker islands have higher Curie temperatures.

Increased interaction energy facilitates reaching low-energy states.

Thermal annealing improves magnetic order in artificial spin ice.

Abstract

We have performed a detailed study of thermal annealing of the moment configuration in artificial spin ice. Permalloy (Ni$_{80}$Fe$_{20}$) artificial spin ice samples were examined in the prototypical square ice geometry, studying annealing as a function of island thickness, island shape, and annealing temperature and duration. We also measured the Curie temperature as a function of film thickness, finding that thickness has a strong effect on the Curie temperature in regimes of relevance to many studies of the dynamics of artificial spin ice systems. Increasing the interaction energy between island moments and reducing the energy barrier to flipping the island moments allows the system to more closely approach the collective low energy state of the moments upon annealing, suggesting new channels for understanding the thermalization processes in these important model systems.