2D Interactions and Binary Crystals of Dipolar and Quadrupolar Nematic Colloids

Abstract

In this Letter, we demonstrate that the symmetry of the elastic interaction between the dipolar and quadrupolar colloidal particles in the nematic liquid crystal leads to a novel variety of 2D nematic "binary" colloidal crystals, which have not been observed in any colloidal system. The dipolar-quadrupolar interaction is highly anisotropic and shows a power-law dependence when the particles approach each other along the director field with a pair-binding energy of the order of several thousands of k(B)T for 4 microm diameter colloids.

Magnetically responsive gourd-shaped colloidal particles in cholesteric liquid crystals

“…Elastic properties of LCs trigger anisotropic interactions between colloids, [1][2][3][4][5][6] directing their self-assembly into macrostructures [7][8][9][10][11][12][13][14] useful, for example, in photonics applications. [11][12][13] During the last decades, experimental and theoretical studies covered different aspects of elastic interactions between spherical colloids mostly in nematic LCs.…”

“…Elastic properties of LCs trigger anisotropic interactions between colloids, [1][2][3][4][5][6] directing their self-assembly into macrostructures [7][8][9][10][11][12][13][14] useful, for example, in photonics applications. [11][12][13] During the last decades, experimental and theoretical studies covered different aspects of elastic interactions between spherical colloids mostly in nematic LCs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Two- [7][8][9][10][11] and three-dimensional 14 crystals were designed in nematics using different elastic dipoles and quadrupoles, and singular defects were tailored using spherical 16 and topologically non-trivial 17 colloidal particles.…”

Capillary-induced giant elastic dipoles in thin nematic films

“…The particle-defect pair forms a neutral unit and is stable contrary to a couple of true topological defects that would annihilate. The self-assembly of particles is then explained by the residual distortion of the matrix far from the pair, which yields long-range elastic interactions between particles (5,6). Whereas the far-distance distortion can be always treated asymptotically, the local director field around the particle depends on several parameters, such as the size and shape of the inclusion or the finite strength of the anchoring, and is accessible only via numerical approaches (7).…”

Nematic colloids, topology and photonics

“…These assemblies are very robust and can be transported as a whole. Several other two-dimensional colloidal crystals have been demonstrated, including quadrupolar colloidal crystals [16] and binary colloidal crystals made up of dipolar and quadrupolar colloids, shown in figure 3f [17]. When small and big colloidal particles are mixed together in the nematic LC, smaller particles tend to decorate the topological defects around bigger particles and hierarchical structures are formed, as presented in figure 3e [19].…”

“…The dipolar and quadrupolar forces between nematic colloidal particles were used to assemble one-dimensional colloidal chains (figure 3a,b) and two-dimensional nematic colloidal crystals of different symmetries [7,8,16,17], shown in figure 3. A two-dimensional colloidal crystal made up of dipolar colloids is presented in figure 3c.…”