Threshold field for switching the de vries S_A^* phase in a low molar mass organosiloxane material

The existence of a threshold field for the onset of switching in the organosiloxane material, ETSiKN65, has been investigated. This material displays a de Vries smectic A^* type phase, and the presence of the threshold confers an anti-ferroelectric-like response. However, it has been found that the value of the threshold depends on the thickness of the specimen, in fact it vanishes altogether if the specimen is more than 20 μm thick. It is concluded that the threshold is due to a complex anchoring mechanism at the interface with the cell walls.