Bilayer artificial spin ice: magnetic force switching and basic thermodynamics

TL;DR

This paper investigates a bilayer artificial spin ice system, revealing how magnetic forces and thermodynamic properties depend on layer separation and monopole configurations, enabling force switching.

Contribution

It introduces a model of bilayer artificial spin ice showing tunable magnetic attraction and repulsion, and analyzes the thermodynamic behavior related to layer separation.

Findings

Layers attract at small separation in ground state

Magnetic monopoles can induce repulsion between layers

Specific heat peak shifts with layer separation

Abstract

We study an artificial spin ice system consisting of two identical layers separated by a height offset $h$. For small separation, the layers are shown to attract each other, provided the whole system is in the ground state. Such an attraction comes about by means of a power-law force that we compare to van der Waals forces. When magnetic monopoles occur in one (or both) layers, the scenario becomes even more interesting and these layers may also repel each other. By tuning parameters like $h$ and monopole distance, switching between attraction and repulsion may be accomplished in a feasible way. Regarding its thermodynamics, the specific heat peak shifts to lower temperature as $h$ increases.