Smectic-A edge dislocations in a very thin cell
Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
2 Laboratory of Physics of Complex Systems, Faculty of Education, University of Maribor, Koroška 160, 2000, Maribor, Slovenia
3 Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia
* e-mail: Milan.firstname.lastname@example.org
Published online: 25 January 2014
We study stable “bookshelf” smectic-A structures within a very thin plane-parallel cell of thickness L in which the mismatch between surface preferred (d s) and intrinsic (d0) smectic layer thicknesses occurs. The Landau-Ginzburg approach based on a complex smectic order parameter is used. For a weak enough smectic positional anchoring strength W smectic layers adopt the modified bookshelf profile. In a thick enough cell with increasing W a lattice of edge dislocations is continuously formed at the confining surfaces and then depinned from them. The structure with dislocations is formed when the condition d 0/(ζ s |d 0/d s − 1|) ∼ 2 is fulfilled, where ζ s is the positional surface anchoring extrapolation length. If the cell is thin enough the dislocations formed at opposite cell plates annihilate and consequently the smectic layers adopt a locked bookshelf structure. This transition is discontinuous and takes place when d 0/(L|d 0/d s − 1|) ∼ 5 is realized. To observe these transitions in a cell of thickness L∼ 1μm the conditions W∼ 10-6 J/m 2 and |d 0/d s − 1| ∼ 5 · 10−4 have to be fulfilled. All the three qualitatively different structures coexist at the triple point.
© EDP Sciences, Springer-Verlag, Società Italiana di Fisica, 2002