Light Scattering from a Surfactant “Sponge” Phase: Evidence for a Hidden Symmetry

Abstract

New light-scattering data from an anomalous isotropic phase in a bilayer-forming surfactant system (sponge phase) are analysed using a Landau-Ginzburg theory with two fluctuating order parameters: one the surfactant density, and the other associated with an "inside/outside" (I/O) symmetry that arises in bilayer-containing systems. The scattering shows a clear signature of this additional order parameters. The concentration dependence of the osmotic compressibility provides strong evidence for fluctuation-induced logarithmic corrections to the elasticity and/or area parameters of the bilayer.