Temperature- and electric-field-induced inverse Freedericksz transition in a nematogen with weak surface anchoring.
We report electric field dependence of the anchoring transition in a mesogen on cooling in a cell with perfluoropolymer treated surfaces. Below a crossover voltage V(co) the transition is discontinuous between planar and homeotropic alignments, and as the temperature is lowered, the transition temperature decreases quadratically with the field. Above V(co) the transition is continuous between planar and tilted alignments, the transition temperature decreasing essentially linearly with the rms field. We develop a simple model to account for these results and argue that the higher field regime corresponds to a temperature driven inverse Freedericksz transition in which the director orientation starts tilting at the weakly anchored surfaces while the tilt angle remains zero at the midplane of the cell.
Kumar
T Arun
TA
School of Physics, University of Hyderabad, Hyderabad 500046, India.
Sathyanarayana
P
P
Sastry
V S S
VS
Takezoe
Hideo
H
Madhusudana
N V
NV
Dhara
Surajit
S