Transition properties of the soft-mode turbulence in the homeotropic electro convection superimposing magnetic fields

The experimental study on transition processes of the spatio-temporal chaos (STC) as well as periodic patterns in homeotropically aligned nematic liquid crystals is reported under superimposing magnetic fields with electric fields. The strong dependence of the threshold for STC on the strength of magnetic fields is observed above certain normalized voltage ε_th, where the two types of STC are found out below and beyond the characteristic value of the magnetic field H* = 620 G. The periodic patterns were observed for the normalized voltage ε below ε_th. Below H* the soft-mode turbulence appears due to the Goldstone mode related to a continuous rotational-symmetry which can be controlled by the application of H. Beyond H*, the conventional STC called defect turbulence, which is similar to STC in the planar system, is observed.