Anisotropic heat transport in the octylcyanobiphenyl (8CB) liquid crystal.

The critical behavior of the specific heat, thermal conductivity, and thermal diffusivity at the smectic-A--nematic phase transition of aligned octylcyanobiphenyl (8CB) has been studied with the photopyroelectric technique. Though the values of the thermal transport parameters are substantially different for homeotropic and planar alignment, it has been shown that the thermal diffusivity critical behavior is characterized by the same critical exponent in the two cases. This result suggests that the mode couplings that govern the critical dynamics associated with the thermal parameters are isotropic. The thermal conductivity remains substantially flat, with only a minor increase close to the transition temperature. \textcopyright{} 1996 The American Physical Society.