Tuning Higher Order Structure in Colloidal Fluids

Colloidal particles self assemble into a wide range of structures under AC electric fields due to induced dipolar interactions [Yethiraj and Van Blaaderen Nature 421 513 (2003)]. Tuning the external field drives structural transitions in the system. Here we consider colloidal fluids comprised of such dipolar particles in experiment and simulation and investigate their 2-body and higher-order structure using a variety of probes. The higher--order structure we probe using three-body spatial correlation functions and a many--body approach based on minimum energy clusters of a related system. These clusters exhibit a cascade of geometric transitions upon increasing the strength of the dipolar interaction, which are echoed in the higher--order structure of the concentrated fluids we study here.