Ice Rule Fragility via Topological Charge Transfer in Artificial Colloidal Ice

TL;DR

This paper explores the unique behaviors of artificial colloidal ice systems, revealing a fragile ice state stabilized by topology and demonstrating how topological charge transfer can spontaneously break this state, unlike traditional spin ices.

Contribution

It introduces the concept of fragile ice in colloidal systems and shows how topological charge transfer can induce spontaneous breaking of ice rules, expanding understanding beyond magnetic spin ices.

Findings

Negative monopoles appear spontaneously in mixed geometries.

The colloidal ice exhibits a fragile manifold where local energetics oppose ice rules.

Topological charge transfer can spontaneously break the fragile ice state.

Abstract

Artificial particle ices are model systems of constrained, interacting particles. They have been introduced theoretically to study ice-manifolds emergent from frustration, along with domain wall and grain boundary dynamics, doping, pinning-depinning, controlled transport of topological defects, avalanches, and memory effects. Recently such particle-based ices have been experimentally realized with vortices in nano-patterned superconductors or gravitationally trapped colloids. Here we demonstrate that, although these ices are generally considered equivalent to magnetic spin ices, they can access a novel spectrum of phenomenologies that are inaccessible to the latter. With experiments, theory and simulations we demonstrate that in mixed coordination geometries, entropy-driven negative monopoles spontaneously appear at a density determined by the vertex-mixture ratio. Unlike its spin-based analogue, the colloidal system displays a "fragile ice" manifold, where local energetics oppose the ice rule, which is instead enforced through conservation of the global topological charge. The fragile colloidal ice, stabilized by topology, can be spontaneously broken by topological charge transfer.