Electric-Field-Induced Phase Separation and Labyrinthine Patterns in Nanocolloids

In this paper we report universal labyrinthine patterns observed in nanocolloids originated from electric-field-induced phase separation. For nanocolloids consisting of magnetic particles (magnetic fluids), the labyrinthine pattern as the result of the co-existence of two phases is found to be stable against perturbation by an additional magnetic field. The relaxation back to the globally disordered pattern after the magnetic field is removed clearly shows evolution of "undulation" thus demonstrates that superimposing magnetic and electric fields can easily manipulate the patterns resulted from the phase separation, indicating that a magnetic fluid has an advantage in exploring the dynamics of defects that has applications in many fields.