Artificial out-of-plane Ising antiferromagnet on the kagome lattice with very small further neighbour couplings

TL;DR

This study investigates how small further-neighbour couplings influence the behavior of artificial kagome lattice Ising antiferromagnets, combining simulations and experiments to understand their role in correlation selection.

Contribution

It demonstrates that even very small further-neighbour couplings significantly affect correlation patterns in artificial kagome Ising antiferromagnets.

Findings

Further neighbour couplings influence spin correlations despite their small magnitude.

Simulations match experimental data, confirming the importance of small couplings.

Small couplings can alter the degeneracy and correlation selection in frustrated systems.

Abstract

Despite their simple formulation, short range classical antiferromagnetic Ising models on frustrated lattices give rise to exotic phases of matter, in particular due to their macroscopic ground state degeneracy. Recent experiments on artificial spin systems comprising arrays of chirally coupled nanomagnets provide a significant strengthening of the nearest neighbour couplings compared to systems with dipolar-coupled nanomagnets. This opens the way to design artificial spin systems emulating Ising models with nearest neighbour couplings. In this paper, we compare the results of an extensive investigation with tensor network and Monte Carlo simulations of the nearest- and further-neighbour ($J_1-J_2-J_{3||}$) kagome Ising antiferromagnet with the experimental spin-spin correlations of a kagome lattice of chirally coupled nanomagnets. Even though the ratios between the further neighbour couplings and the nearest neighbour coupling estimated from micromagnetic simulations are much smaller than for dipolar-coupled nanomagnets, we show that they still play an essential role in the selection of the correlations.