Chiral switching and relaxation dynamics in artificial square ice

The relaxation kinetics and emerging correlations of arrays of interacting Ising-like nanomagnets are governed by the switching rates of the individual magnets. These rates depend, via the Arrhenius law, on the energy barrier for moment reversal in the nanomagnets. In this work, we consider how the switching behaviour of a nanomagnet in archetypical artificial square ice is modified by the interaction with its six nearest neighbours, and find that barrier energies for clockwise and counter-clockwise rotation can differ significantly. This effect is relevant for both exchange- as well as magnetostatically-dominated moment reversal. From string-method simulations we obtain further dynamical reductions of the switching barriers, as the micromagnetic structure evolves during reversal. The barrier splitting leads to an exponential enhancement of the transition rates compared to mean-field predictions. Finally, these modifications lead to faster relaxation dynamics and different spatial correlations in kinetic Monte Carlo simulations.