Wetting-driven Casimir force in nematic liquid crystals

We study the fluctuation-mediated structural interaction between identical order-inducing substrates immersed in the isotropic phase of a liquid cryst al. We show that because of the presence of substrate-stabilized nematic we tting layers, the force due to thermal fluctuations of nematic order is rep ulsive rather than attractive, which is in contrast with the standard pseud o-Casimir force between like walls. Contrary to expectations, this interact ion is characterized by the same range as the mean-field attraction. [S0031 -9007(99)08386-6].