Colloidal Dimers on a Honeycomb Magnetic Lattice

Geometric Frustration of Colloidal Dimers on a Honeycomb Magnetic Lattice. 
Pietro Tierno
Phys. Rev. Lett. 116, 038303 (2016)

(a) Schematic of the FGF film with a magnetic bubble lattice subjected to an external field Hz. One Wigner-Seitz unit cell is shaded in blue with one paramagnetic colloid. For Hz=0, the lattice constant is a=11.6  μm and the radius R=4.2  μm. (b) Normalized distance r/a of one paramagnetic colloid from the center of a magnetic bubble versus Hz. (c) Normalized energy landscape for a FGF under a static field Hz=0.17Ms. The inset shows a 3D view of one triangular minimum. (d) Snapshots of a small section (48×42  μm2) of a magnetic bubble lattice filled with n=1, 2, 3 particles per pinning site (scale bar is 10  μm). Schematics at the bottom show the corresponding configurations in a triangular minimum.