Thermal conductivity of the nematic liquid crystal 4-n-pentyl-4’-cyanobiphenyl

We report experimental results for the thermal conductivities of 4-n-pentyl-4'-cyanobiphenyl (5CB) for 19 \ifmmode^\circ\else\textdegree\fi{}CT48 \ifmmode^\circ\else\textdegree\fi{}C. For T${\mathit{T}}_{\mathit{N}\mathit{I}}$=35.17 \ifmmode^\circ\else\textdegree\fi{}C this substance is a nematic liquid crystal, where ${\mathit{T}}_{\mathit{N}\mathit{I}}$ is the nematic-isotropic transition temperature. The conductivities were determined by measuring the temperature difference across a horizontal layer of the fluid heated from below in magnetic fields either parallel or perpendicular to the heat current. The field magnitude was much larger than the Fr\'eedericksz field. For T${\mathit{T}}_{\mathit{N}\mathit{I}}$, this yielded monodomain samples with the director oriented parallel to the field, and thus the conductivities ${\ensuremath{\lambda}}_{\mathrm{\ensuremath{\parallel}}}$ and ${\ensuremath{\lambda}}_{\mathrm{\ensuremath{\perp}}}$ with the director parallel and perpendicular to the heat current, respectively.