Double helices folding half parabolic focal conics in chiral smectics

Abstract

In this paper, we report the existence of a double helix folding a part of one of two cofocal parabolae. We observe the winding/unwinding of the double helix as temperature is changed and this mechanism is accompanied here by a change of the latus rectum p of the corresponding parabola. We propose a model of the layers inside and outside the double helix consistent with experimental observations.

Keywords:

• defects
• focal conic domains
• parabolic focal conic domains
• smectic A

Notes

1.One can see that the nature of the transformation SH towards DH is still not known.