Sedimentation profiles of systems with reentrant melting behavior

We examine sedimentation density profiles of star polymer solutions as an example of colloidal systems in sedimentation equilibrium that exhibit reentrant melting in their bulk phase diagram. Phase transitions between a fluid and a fluid with an intercalated solid are observed below a critical gravitational strength alpha*. Characteristics of the two fluid-solid interfaces in the density profiles occurring in Monte Carlo simulations for alpha<alpha* are in agreement with scaling laws put forth in the framework of a phenomenological theory. Furthermore, we detect density oscillations at the fluid-gas interface at high altitudes for high-gravitational fields, which are verified with density-functional theory and should be observable in surface scattering experiments.