Line contribution to the critical Casimir force between a homogeneous and a chemically stepped surface. (12th May 2015)

• Record Type: Journal Article
• Authors: Toldin, Francesco Parisen; Tröndle, Matthias; Dietrich, S
• Is Part Of: Journal of physics. Volume 27:Number 21(2015)
• Publication Date: 2015-05-12
• Subjects: critical Casimir force -- critical phenomena -- Monte Carlo simulations -- mean-field theory -- finite-size scaling -- liquid thin films; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/27/21/214010
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Recent experimental realizations of the critical Casimir effect have been implemented by monitoring colloidal particles immersed in a binary liquid mixture near demixing and exposed to a chemically structured substrate. In particular, critical Casimir forces have been measured for surfaces consisting of stripes with periodically alternating adsorption preferences, forming chemical steps between them. Motivated by these experiments, we analyze the contribution of such chemical steps to the critical Casimir force for the film geometry and within the Ising universality class. By means of Monte Carlo simulations, mean-field theory and finite-size scaling analysis we determine the universal scaling function associated with the contribution to the critical Casimir force due to individual, isolated chemical steps facing a surface with homogeneous adsorption preference or with Dirichlet boundary condition. In line with previous findings, these results allow one to compute the critical Casimir force for the film geometry and in the presence of arbitrarily shaped, but wide stripes. In this latter limit the force decomposes into a sum of the contributions due to the two homogeneous parts of the surface and due to the chemical steps between the stripes. We assess this decomposition by comparing the resulting sum with actual simulation data for the critical Casimir force in the presence of a chemically striped substrate.