Fluctuation-induced Kerr effect near the smectic-A-smectic-C-alpha* phase transition

The anomalous increase of Kerr effect due to pretransitional fluctuations h as been investigated in the SmA phase close to the SntA-SmCalpha* transitio n point in antiferroelectric liquid crystals MHPOBC and MHPOCBC. We have de veloped a Landau theory taking into account the fluctuations and shown that there are two contributions to the Kerr effect. On the basis of theoretica l results. the experimental results obtained in MHPOBC and MHPOCBC were dis cussed and a clear evidence of the fluctuation-induced Kerr effect was pres ented.