We study theoretically the smectic-$A$ to -$C$ phase transition in isotropic disordered environments. Surprisingly, we find that, as in the clean smectic-$A$ to -$C$ phase transition, smectic layer fluctuations do not affect the nature of the transition, in spite of the fact that they are much stronger in the presence of the disorder. As a result, we find that the universality class of the transition is that of the “random field $XY$ model” ($RFXY$).

• Received 12 June 2012

DOI:https://doi.org/10.1103/PhysRevE.87.042501