Casimir effect in fluids above the isotropic-lamellar transition.
We study fluctuation-induced interaction in confined fluids above the isotropic-lamellar transition. At an ideally continuous transition, the disjoining pressure has the asymptotic form Pi(d-->infinity) approximately -Ck(B)Tq(2)(0)/d, where d is the interwall distance, q(0) is the wave number of the scattering peak, and C = 1/4pi in the strong anchoring limit. The long-rangedness is enhanced due to continuous distribution of soft modes in the q space. An unconventionally strong Casimir force with a range of several lamella thicknesses is realistic above the transition. We also find an oscillatory force profile near a surface-induced transition.
Uchida
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Department of Physics, Kyoto University, Kyoto 606, Japan.