Optimizing Thermalization Process for Square Artificial Spin Ice

Artificial spin ice systems are arrays of two-dimensional nanoscale islands, each of which possesses a discrete magnetic moment pointing along easy axis, that are used to study collective behavior of interacting magnetic systems. Square artificial spin ice has a well-defined ground state, and previous studies have reported that high temperature annealing can thermalize these systems into that ground state. We used Magnetic Force Microscope (MFM) imaging of the magnetic moment configuration after thermal treatments to study the effectiveness of different annealing protocols of this system. By varying temperature profiles and island dimensions, we explored a set of parameters to optimize thermal treatment and study the thermalization effect for arrays of islands with varying thickness and lateral dimensions. This work can be extended to better thermalize other artificial spin ice systems, such as the kagome lattice and will help us to understand the underlying mechanism of the thermalization process.