This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In a recent Nature Communications study, researchers have reported the realization of an anti-spin ice, a system that does the opposite of conventional spin ices by breaking the ice rule that governs them. Spin ices are magnetic systems that mimic a rule found in water ice.
In water ice, each oxygen atom keeps two hydrogen atoms close and two farther away. This is known as the ice rule. Because many arrangements satisfy this rule equally well, the hydrogen atoms in ice end up being disordered, meaning that there's no repeating pattern.
This is a sign of geometric frustration, which occurs when competing interactions in a system can't all be satisfied at once, leaving many equally good compromises. Scientists have recreated this behavior in engineered systems called artificial spin ices, built from arrays of tiny magnets or microscopic particles called colloids. In colloidal ices, particles sit in tiny grooves, or wells, arranged along a lattice, each resting near one end or the other.
Because the particles repel each other, they spread out evenly, keeping the imbalance of particles at each junction (its topological charge) as small as possible. For the most part, researchers have studied colloidal ices using repulsive particles. In the new study, researchers examined what happens when the particles attract each other instead, creating what they call an anti-spin ice.
Phys.org spoke with co-author of the study Pietro Tierno from the University of Barcelona. Tierno said that the work "was motivated by the idea that changing something as fundamental as the sign of the pair interaction between the particles—from repulsive to attractive—might completely change the way geometric frustration emerges in a physical system." In colloidal ice, each groove holds a single particle and links two vertices of the lattice. The particle can sit near either vertex, acting like a tiny arrow, or spin, that points toward one vertex and away from the other.
Researchers use these arrows to give each vertex a topological charge. They count how many particles sit close to the vertex and how many sit far away, and the difference gives the charge. On a square lattice, each vertex is surrounded by four grooves.
Extract — continue reading at the source.
