Nanoparticle controlled nematic macroscopic properties

Abstract

The impact of the weak disorder on systems exhibiting long-range order is of interest for all branches of condensed matter systems and is still relatively weakly explored. Experimentally adequate schemes for such purpose are homogenous mixtures of nematic liquid crystals (LCs) and appropriate nanoparticles (NPs), whose characteristic linear size R ranges between nm and several micrometers. In such systems, NPs in most cases impose a random field-type of disorder due to local NP-induced symmetry breaking. The resulting disorder strength can be fine-tuned by varying several parameters: kind of NPs (conducting, semiconducting, non-conducting), their geometry, R, distribution of R values, NPs’ surface treatment. Furthermore, the resulting NP-LC configurations could be exploited for several applications, in particular in the realm of light-manipulation devices. We carried out a numerical study, where we explore systematically the impact of a relatively weak NP-induced disorder on nematic macroscopic LC order. The semi microscopic Lebwohl-Lasher-type model was used, where different control parameters were varied (concentration and partial orientational order of NPs, LCNP interaction strength, temperature). Research outcomes could be useful mostly for applications based on disorder-controlled tunable LC optical properties.