Tuning magnetic order in artificial spin ices: thermalisation, disorder and non-equilibrium phenomena

Artificial spin ices are arrays of correlated nano-scale magnetic islands that prove an excellent playground in which to study critical phenomena. In this contribution, we discuss how both geometry and the coupling of islands to external fields influence magnetic order. Using Lorentz transmission electron microscopy, we study a transition between antiferromagnetic and ferromagnetic order across a continuum of spin ice geometries. We show how emergent anisotropies can arise in field-driven processes and how relaxation timescales can be adjusted locally within arrays through a coupling to a site-specific bias field. Our work demonstrates artificial spin ice as an excellent testbed in which to probe non-equilibrium phenomena in low-dimensional systems.