Existence of a Sm-C Grain Boundary Phase at the Chiral MAC Point

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Abstract
Based on a mean field analysis of the Chen-Lubensky model we extend an earlier discussion regarding the effect of chirality on the region of the phase diagram where the Cholesteric, Smectic-A, and Smectic- C* phases meet (i.e., the N* AC* point). We show that, on the Sm-C* side of the phase diagram, a second twist grain boundary (or chiral smectic) phase occurs. This phase, the “TGB C ”, is a highly dislocated version of Smectic-C. According to the deGennes analogy, this phase corresponds to Abri- kosov's flux lattice when the Ginzburg parameter K is negative. We also show that an Ising like transition between the TGB A and TGB C occurs and that this phase boundary, together with the Sm-A/TGB A Sm-C/TGBc, and the x-y like Sm-A/Sm-C* phase boundaries, meet at a multicritical point.