A Novel Route to Defect Turbulence in Nematics

A novel cascade of instabilities involving 3 wavelength doubling transitions to turbulent patterns has been observed in EHC when the director boundary conditions are homeotropic and there is no flow alignment. Above the Fréedericksz transition, the first instability is an oscillatory pattern with the roll axes at an angle to the director. At slightly higher voltages there is a transition to a Standing Stripe Pattern that in turn transforms to a curved roll pattern nucleated by a regular array of S=+½ line defects (Möbions). We call this pattern the Zvinger pattern, a cage for wild animals, the S=+½'s. These observations provide important complementary information for theories based on small amplitude perturbations of a highly nonlinear base state.