Field-Induced Changes in Symmetry

In fact, we have already considered an example a field-induced tilt in the smectic A phase, thus a change in symmetry from I ooh to C2h- The induced tilt angle is proportional to the field squared and factor Tca/T — TcaV where 7 1.3 [31]. For small AT the field-induced biaxiality can be measured by optical methods. 

Another example of the symmetry change is the field-induced biaxiality 

For subsequent discussion (1.1) must be generalized. The orientational order at a point r in a nematic liquid crystal is defined by the ordering matrix 

Now Q (and B) are presented in terms of the director fluctuations which are not assumed to be isotropic in the x, y-plane. For nl = the biaxial parameter vanishes and the uniaxial one becomes equal to (1.1). When the field is applied, for example, along the x-direction, and xx = yy =  

The field-induced biaxiality has been observed in a planarly oriented layer of compound 

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