Ring-pattern dynamics in smectic-C* and smectic-C*A freely suspended liquid crystal films

Area of Science:

• Materials Science
• Soft Matter Physics
• Liquid Crystals

Background:

• Freely suspended chiral smectic-C films exhibit complex molecular orientation patterns.
• External electric fields can induce dynamic changes in liquid crystal structures.

Purpose of the Study:

• To investigate the formation and dynamics of ring patterns of 2pi solitons in chiral smectic-C films.
• To quantitatively describe these dynamics using a simple model.
• To explore layer number effects on relaxation rates in different chiral smectic-C materials.

Main Methods:

• Observation of ring pattern formation under in-plane rotating electric fields.
• Measurement of driven dynamics during synchronous winding.
• Measurement of zero-field relaxation dynamics of ring patterns.
• Development of a quantitative model for low polarization DOBAMBC.
• Comparison of relaxation rates in odd and even layer number TFMHPOBC films.

Main Results:

• Concentric 2pi soliton ring patterns form in response to rotating electric fields.
• A simple model quantitatively describes ring formation and relaxation in DOBAMBC.
• An odd-even layer number effect was observed in TFMHPOBC, with odd layers relaxing slower.
• This rate difference is attributed to significantly larger spontaneous polarization in odd layer number films.

Conclusions:

• The study elucidates the dynamics of soliton ring formation in chiral smectic-C films.
• A model provides quantitative insight into these phenomena.
• Spontaneous polarization plays a critical role in the relaxation dynamics, particularly showing an odd-even layer effect.