Magnetic field driven dynamics in twisted bilayer artificial spin ice at superlattice angles

TL;DR

This study uses numerical simulations to explore how magnetic behaviors in twisted bilayer artificial spin ice are influenced by layer rotation and separation, revealing unique magnetic orderings at specific angles.

Contribution

It introduces a detailed simulation analysis of bilayer artificial spin ice with layer rotation, highlighting the impact of superlattice angles on magnetic dynamics and ordering.

Findings

Unusual magnetic orderings predicted at specific superlattice angles.

Magnetization dynamics are significantly affected by layer rotation and separation.

Domain configurations vary with layer alignment, influencing reversal processes.

Abstract

Geometrical designs of interacting nanomagnets have been studied extensively in the form of two dimensional arrays called artificial spin ice. These systems are usually designed to create geometrical frustration and are of interest for the unusual and often surprising phenomena that can emerge. Advanced lithographic and element growth techniques have enabled the realization of complex designs that can involve elements arranged in three dimensions. Using numerical simulations employing the dumbbell approximation, we examine possible magnetic behaviours for bilayer artificial spin ice (BASI) in which the individual layers are rotated with respect to one another. The goal is to understand how magnetization dynamics are affected by long-range dipolar coupling that can be modified by varying the layer separation and layer alignment through rotation. We consider bilayers where the layers are both either square or pinwheel arrangements of islands. Magnetic reversal processes are studied and discussed in terms of domain and domain wall configurations of the magnetic islands. Unusual magnetic ordering is predicted for special angles which define lateral spin superlattices for the bilayer systems.