Topology by Design in Magnetic nano-Materials: Artificial Spin Ice

TL;DR

This paper reviews the development of artificial spin ice materials, emphasizing how modern nano-fabrication enables the design of topologically exotic magnetic states with potential applications in controlling collective dynamics.

Contribution

It introduces the concept of topology by design in magnetic nano-materials, highlighting recent advances in fabricating and characterizing artificial spin ice with tailored geometries and topological properties.

Findings

Real-time, real-space characterization of magnetic nano-structures

Design of artificial spin ice with specific topological states

Implications for controlling collective magnetic dynamics

Abstract

Artificial Spin Ices are two dimensional arrays of magnetic, interacting nano-structures whose geometry can be chosen at will, and whose elementary degrees of freedom can be characterized directly. They were introduced at first to study frustration in a controllable setting, to mimic the behavior of spin ice rare earth pyrochlores, but at more useful temperature and field ranges and with direct characterization, and to provide practical implementation to celebrated, exactly solvable models of statistical mechanics previously devised to gain an understanding of degenerate ensembles with residual entropy. With the evolution of nano--fabrication and of experimental protocols it is now possible to characterize the material in real-time, real-space, and to realize virtually any geometry, for direct control over the collective dynamics. This has recently opened a path toward the deliberate design of novel, exotic states, not found in natural materials, and often characterized by topological properties. Without any pretense of exhaustiveness, we will provide an introduction to the material, the early works, and then, by reporting on more recent results, we will proceed to describe the new direction, which includes the design of desired topological states and their implications to kinetics.