Fig. 4: External control of equilibrium pattern.
From: Interactions and pattern formation in a macroscopic magnetocapillary SALR system of mermaid cereal
a When a magnetic strip is placed below the bath, the disks are pulled downwards, increasing the capillary attraction force. If tuned correctly, fully repulsive disks can transition to mermaid disks under this additional force. b leq as a function of m from the magnetocapillary model for a = 2.5 mm, and M = 9 A ⋅ cm2. The dashed line shows the physical value of m while the dotted dashed-line shows the effective m after applying the external magnetic force based on the leq value extracted from the experiments shown in the inset. c The hexagonal lattice state (on the left) transitions to the striped pattern (right) by adding the magnetic strip below the bath for disks with a = 2.5 mm, M = 9 A ⋅ cm2, and m = 0.09 g (Bo = 1.05, \({{{{{{{\mathcal{M}}}}}}}}\) = 3.5) and ϕ = 0.18. The scale bar indicates 2 cm. d Sample magnetocapillary simulations for a = 2.5 mm, and M = 9 A ⋅ cm2 showing phase transition from hexagonal lattice to stripes when m changes from 0.09 g to 0.115 g (Bo = 1.05 with \({{{{{{{\mathcal{M}}}}}}}}\) decreasing from 3.5 to 1.9) for ϕ = 0.18.
