Ignoring your neighbors: Moment correlations dominated by indirect or distant interactions in an ordered nanomagnet array

TL;DR

This study investigates how indirect and distant interactions influence moment correlations in ordered nanomagnet arrays, revealing that these interactions can dominate over direct pairwise interactions depending on lattice parameters.

Contribution

It demonstrates that in nanomagnet arrays, indirect and long-range interactions can override direct interactions, which was previously underappreciated in such systems.

Findings

Correlations can have opposite signs to direct interactions.

Indirect interactions can dominate in certain lattice configurations.

Tuning lattice parameters controls the nature of magnetic correlations.

Abstract

We have studied the moment correlations within triangular lattice arrays of single-domain co-aligned nanoscale ferromagnetic islands. Independent variation of lattice spacing along and perpendicular to the island axis tunes the magnetostatic interactions between islands through a broad range of relative strengths. For certain lattice parameters, the sign of the correlations between near-neighbor island moments is opposite to that favored by the pair-wise interaction. This finding, supported by analysis of the total correlation in terms of direct and convoluted indirect contributions across multiple pairwise interactions, indicates that indirect interactions and/or those mediated by further neighbors can be tuned to be dominant, with implications for the wide range of systems composed of interacting nanomagnets.