Frustration in colloidal artificial ices

Engineering of frustration in colloidal artificial ices realized on microfeatured grooved lattices.
Antonio Ortiz-Ambriz, Pietro Tierno
Nature Comms. 7, 10575 (2015)

(a) Schematic view of the colloidal spin ice made by a honeycomb lattice of double-well islands filled with paramagnetic colloids. The applied field B perpendicular to the plane induces repulsive dipolar interactions between the particles. (b) Optical profilometer image of the honeycomb spin ice, and (c) the cross-section of a double well with a small central hill, giving a gravitational potential U_g. (d,e) Equilibrium state of a honeycomb ice (d) (lattice constant a=44 μm) and a square ice (e) (lattice constant a=33 μm). Blue arrows denote spin direction, while green circles highlight vertices of type K_II (in d) and S_III (in e). Scale bars, 20 μm for all images. (f,g) Vertex configurations for honeycomb (f) and square (g) ices. The lowest panel shows the normalized magnetostatic energy for each type of vertex.