Site-specific attraction dynamics of surface colloids driven by gradients of liquid crystalline distortions.

The site-specific migration dynamics of small particles at the air-nematic liquid crystal (LC) interface is investigated, using a LC film with a unique gradient of LC distortions. This gradient has been identified as the direct origin of the site-specific migration, while the elastic multipole interaction between the pre-existing distortion and that induced around particles is negligible. The results reveal a basic behavior of small particles with weak anchoring strength in LC distortions, which is often hidden in prominent elastic multipole interactions typically found with larger particles. Moreover, the present mechanism of the site-specific attraction of particles is specifically relevant to directed patterning and manipulations of nano-particles in nematic LCs with distortions.