Svensek Daniel, Pleiner Harald, Brand Helmut R
Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1111 Ljubljana, Slovenia.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Aug;78(2 Pt 1):021703. doi: 10.1103/PhysRevE.78.021703. Epub 2008 Aug 6.
For cholesteric and chiral smectic liquid crystals a rotation of the helical superstructure can be induced for suitable boundary conditions for external fields such as temperature gradients and electric fields: the Lehmann effect. Here we predict that the inverse effect can lead to a pump for particles and ions on a length scale of microns: When a spatial pattern such as a phase winding pattern or a spiral is generated, for example, for a freely suspended smectic C* film, a concentration current arises. We also point out that this concentration current is, under suitable experimental conditions, accompanied by a heat current and/or an electric current. Similar effects are expected for cholesterics, smectic F* and I* as well as for Langmuir monolayers, since all of these systems share the property of macroscopic chirality.
