Anomaly in the dynamic behavior of the electroclinic effect below the nematic–smectic-A phase transition

The electroclinic effect and dielectric response have been investigated in the British Drug House material SCE12 over its entire 15-K smectic-A range. Near the smectic-A–smectic-${\mathit{C}}^{\mathrm{*}}$-phase transition both the electroclinic coefficient and dynamic response behave normally, the former diverging and the latter exhibiting a critical slowing down on approaching ${\mathit{T}}_{\mathit{A}\mathrm{-}\mathit{C}}^{\mathrm{*}}$ from above. Similar behavior is seen in the dielectric response. Approximately 10 to 12 K above ${\mathit{T}}_{\mathit{A}\mathrm{-}\mathit{C}}^{\mathrm{*}}$, however, it was found that the electroclinic relaxation time levels off and even begins to increase again on approaching the nematic–smectic-A transition from below. The magnitude of the electroclinic coefficient, however, decreases monotonically on approaching the nematic–smectic-A transition.