TRANSIENT STRUCTURES IN THE TWIST FREEDERICKSZ TRANSITION OF LOW-MOLECULAR-WEIGHT NEMATIC LIQUID-CRYSTALS

We have investigated the evolution of transient structures in the twis t Freedericksz transition of low-molecular-weight nematic liquid cryst als. Planarly aligned cells have been exposed to an in-plane external magnetic field perpendicular to the initial director orientation. The formation of periodic structures was studied by conventional microscop y. We observed a complex director deformation showing an induced out-o f-plane tilt. We describe the formation of periodic long-term stable t wist-bend inversion walls which can be observed up to several hours af ter their appearance. The wavelengths of the structures determined exp erimentally are discussed and compared to theoretical predictions.