We measure optically the quadrupolar order S induced by a stabilizing electric field E in the isotropic phase of the nematogenic 4’-n-pentyl-4-cyanobiphenyl, with large positive dielectric anisotropy ${\mathrm{\epsilon }}_{\mathit{a}}$∼10. For high enough field and low enough temperature, a paranematic-nematic first-order transition is induced, with a critical point at ${\mathit{E}}_{\mathit{c}}$=1.41×${10}^5$ V/cm, ${\mathit{T}}_{\mathit{c}}$=${\mathit{T}}_{\mathit{N}\mathit{I}}$+0.65 K, and ${\mathit{S}}_{\mathit{c}}$=0.15, where ${\mathit{T}}_{\mathit{N}\mathit{I}}$ is the nematic-isotropic phase-transition temperature.

• Received 14 April 1993

DOI:https://doi.org/10.1103/PhysRevE.48.3822