Dependence of energy barrier reduction on collective excitations in square artificial spin ice: A comprehensive comparison of simulation techniques

TL;DR

This study uses micromagnetic simulations to analyze energy barriers in square artificial spin ice, revealing that detailed modeling significantly lowers barrier estimates compared to simpler methods, impacting lifetime predictions.

Contribution

It provides a comprehensive comparison of simulation techniques for energy barriers in artificial spin ice, highlighting the importance of detailed micromagnetic modeling.

Findings

Micromagnetic simulations show up to 35% lower energy barriers than mean barrier approximation.

Lower barriers imply up to seven orders of magnitude reduction in expected lifetime.

Proper modeling of collective excitations is crucial for accurate energy barrier estimation.

Abstract

We perform micromagnetic simulations to study the switching barriers in square artificial spin ice systems consisting of elongated single domain magnetic islands arranged on a square lattice. By considering a double vertex composed of one central island and six nearest neighbor islands, we calculate the energy barriers between two types of double vertices by applying the string method. We investigate by means of micromagnetic simulations the consequences of the neighboring islands, the inhomogeneities in the magnetization of the islands and the reversal mechanisms on the energy barrier by comparing three different approaches with increasing complexity. The micromagnetic models, where the string method is applied, are compared to the currently common method, the mean barrier approximation. Our investigations indicate that a proper micromagnetic modeling of the switching process leads to significantly lower energy barriers, by up to 35% compared to the mean-barrier approximation, so decreasing the expected average life time up to seven orders of magnitude. Hereby, we investigate the influence of parallel switching channels and the conceptional approach of using a mean-barrier to calculate the corresponding rates.