Temperature induced transition of spin dimensionality in magnetic metamaterials

Spin and spatial dimensionalities are universal concepts, essential for describing both phase transitions and dynamics in magnetic materials. Lately, the same ideas have been adopted and used to describe some of the properties of magnetic metamaterials. Arrays of mesoscopic magnets, or mesospins, have been utilised to replicate and explore systems belonging to different universality classes. Here we discuss a system which does not conform to the conventional use of the ideas behind universality, as the mesospins can change their spin dimensionality between 0 (vortex) and 2 (XY-like). The transitions are enabled by nucleation and annihilation of vortex cores, shifting the topological charges between the interior and the edges of the elements. The results provide insight into how dynamics at different length scales couple, leading to non-trivial thermally driven topological transitions in magnetic metamaterials.