Emergent charge crystallization and frustration in a particle anti-spin Ice

TL;DR

This paper introduces the first realization of an anti-spin ice system where the system maximizes topological charge instead of minimizing it, revealing new types of frustration and order in artificial spin ices.

Contribution

It demonstrates the creation of an anti-spin ice with inverted charge rules, explores its behavior across various lattice geometries, and uncovers novel frustration phenomena.

Findings

Anti-spin ice system seeks to maximize, not minimize, spin ice charges.

Lattice connectivity induces a new form of topological charge frustration.

Anti-spin ice exhibits charge crystallization and frustration depending on geometry.

Abstract

Artificial spin ices have transcended their origins in frustrated rare-earth pyrochlores to become a versatile platform for engineering exotic states of matter. Across diverse implementations, from nanomagnets and superconducting vortices to colloids, quantum annealers, liquid crystals, and metamaterials, they are unified by the ice rule, which often leads to degeneracy and constrained disorder by enforcing minimization of the local topological charge. Here, we report the first realization of an "anti-spin ice" in which not only the ice rule does not hold, but its opposite is true as the system seeks to maximize, rather than minimize, spin ice charges. Using fast-rotating, in-plane magnetic fields to generate isotropic attraction between colloidal particles, we invert the conventional paradigm of repulsive interactions in colloidal spin ices. Combining experiments and simulations across standard square and honeycomb lattices as well as novel pentaheptite geometries, we establish rules for order and disorder in the anti-spin ice. With the pentaheptite lattice, we demonstrate that the anti-spin ice system can also exhibit frustration, but of a new kind. This topological charge frustration arises from the lattice connectivity, where networks of unequal, odd-sided polygons suppress charge crystallization at high interaction strength.