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DY: Fachverband Dynamik und Statistische Physik

DY 41: Poster - Pattern/ Nonlinear Dyn./ Fluids/ Granular/ Critical Phen.

DY 41.48: Poster

Donnerstag, 3. April 2014, 17:00–19:00, P3

Critical Casimir force in the presence of random local adsorption preference — •Francesco Parisen Toldin — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Germany

We study the critical Casimir force for a film geometry in the Ising universality class. We employ a homogeneous adsorption preference on one of the confining surfaces, while the opposing surface displays quenched random disorder, leading to a random local adsorption preference. Disorder is characterized by a parameter p which measures, on average, the portion of the surface which prefers one component, so that p=0,1 correspond to homogeneous adsorption preference. By means of Monte Carlo simulations of an improved Hamiltonian and finite-size scaling analysis, we determine the critical Casimir force and the associated universal scaling function. We show that by tuning the disorder parameter p the system exhibits a crossover between an attractive and a repulsive force. At p=0.5 disorder allows to effectively realize Dirichlet boundary conditions, which are generically not accessible in classical fluids. Our results are relevant for the experimental realizations of the critical Casimir force in binary liquid mixtures.

Ref: F. Parisen Toldin, arXiv:1308.5220