Nearly-second-order nematic-isotropic phase transition in a cyclic thermotropic liquid crystal

Kerr measurements are reported for a cyclic trimeric liquid crystal above the uniaxial nematic-isotropic phase transition temperature ${\mathit{T}}_{\mathit{N}\mathit{I}}$. The inverse of the order-parameter susceptibility is found to be linear in temperature, such that the quantity ${\mathit{T}}_{\mathit{N}\mathit{I}}$-${\mathit{T}}^{\mathrm{*}}$ is less than 200 mK, where ${\mathit{T}}^{\mathrm{*}}$ is the supercooling limit of the isotropic phase. Well below ${\mathit{T}}_{\mathit{N}\mathit{I}}$ we observe textures consistent with a biaxial nematic phase.