We show how the low-frequency dependence of the proton spin-lattice relaxation time $T_1(\nu )$ of octylcyanobiphenyl liquid crystals confined in high-density silica gels evidences a long-range order nematic phase in spite of the strong confinement and random disorder of the gels. The universal value and frequency dependence observed, $T_1(\nu )\propto {\nu }^{2/3}$, is interpreted within a relaxation model due to director fluctuations in nematic liquid crystals confined to mass fractal porous media. The model provides a relation $T_1(\nu )\propto {\nu }^{2-d/2}$, giving a reliable value of the structural fractal dimension $d_f=2.67$ for all the host silica gels.

• Received 21 December 2003

DOI:https://doi.org/10.1103/PhysRevLett.92.195504