Frustration, the presence of constraints/interactions that cannot be completely satisfied, is ubiquitous in the physical sciences as well as in life and a source of degeneracy and disorder which gives rise to new and interesting physical phenomena. In the past years a new perspective has opened in the study of frustration through the creation of artificial frustrated magnetic systems, consisting of arrays of lithographically fabricated single-domain ferromagnetic nanostructures that behave like giant Ising spins. The interactions can be controlled through their geometric properties and arrangement: The degrees of freedom of the material can be directly tuned, but also individually observed. Experimental studies have unearthed intriguing connections to the out-of-equilibrium physics of disordered systems and non-thermal “granular” materials, while revealing strong analogies to spin ice materials and their fractionalized magnetic monopole excitations, lending the enterprise a distinctly interdisciplinary flavor.
In this talk we outline the more recent developments and future vistas for progress in this rapidly expanding field. We show how recent results have opened paths to new territories. Higher control, inclusive of genuine thermal ensembles have replaced the earlier and coarser methods based on magnetic agitation. Dynamical versions are now being realized, characterized in real time via PEEM, revealing statistical mechanics in action. This has lead us to afford implementation of new geometries, not found in nature, for dedicated bottom up design of desired emergent properties. Born as a scientific toy to investigate frustration-by-design, artificial spin ice might now be used to open “a path into an uncharted territory, a landscape of advanced functional materials in which topological effects on physical properties can be explored and harnessed.”
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