Additional contribution, with no critical thermal behavior, to the optical Kerr constant of nematogens in their isotropic phases

The authors report on optical Kerr effect measurements performed in the isotropic phase of the nematogen $p$-methoxy-benzoate-$p$-$n$-pentylbenzene. The optical Kerr constant is found to obey the well-known ${(T-T^{*})}^{-1\mathrm{}}$-type law near the isotropic-nematic transition temperature, but to deviate from it at higher temperatures. An argument is presented for the existence of a roughly temperature-independant mechanism involved in the response of isotropic phases of nematogens to an intense electric field. A possible microscopic interpretation is suggested.