| Chaos or spatiotemporal chaos is usually associated with disordered state. However, in a new type of spatiotemporal chaos called Soft-Mode Turbulence (SMT) observed in electroconvection of homeotropic nematic systems and generated by the nonlinear interaction between the Nambu-Goldstone modes and the convective modes, we reveal a hidden order by introducing pattern ordering $M_p$ as an order parameter to measure the degree of order of the convective pattern. We found that two types of SMT pattern called oblique roll and normal roll patterns correspond to, respectively, disordered and ordered states due to zero and finite $M_p$ where the so-called Lifshitz frequency is the transition point. The order-disorder transition is originated from the different symmetry of nonlinear interaction between the Nambu-Goldstone modes and the convective modes for the oblique and the normal rolls. |
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