Dielectric Properties of Di-$n$-Heptyl Azoxybenzene in the Nematic and in the Smectic-$A$ Phases

We report the dielectric constants of $p$, $p^{\prime }$-di-$n$-heptyl azoxybenzene in the nematic and in the smectic-$A$ phase. Around the nematic-smectic transition ${\epsilon }_{\parallel }$ decreases with decreasing temperature while ${\epsilon }_{\perp }$ increases anomalously. This is explained by an increased dipolar correlation between the molecules due to the formation of the smectic planes.